Forms. The bane of the Web developer brought to you in all its gory detail.
Introduction
This section is non-normative.
A form is a component of a Web page that has form controls, such as text fields, buttons,
checkboxes, range controls, or colour pickers. A user can interact with such a form, providing data
that can then be sent to the server for further processing (e.g. returning the results of a search
or calculation). No client-side scripting is needed in many cases, though an API is available so
that scripts can augment the user experience or use forms for purposes other than submitting data
to a server.
Writing a form consists of several steps, which can be performed in any order: writing the user
interface, implementing the server-side processing, and configuring the user interface to
communicate with the server.
Writing a form's user interface
This section is non-normative.
For the purposes of this brief introduction, we will create a pizza ordering form.
Any form starts with a form element, inside which are placed the controls. Most
controls are represented by the input element, which by default provides a one-line
text field. To label a control, the label element is used; the label text and the
control itself go inside the label element. Each part of a form is considered a
paragraph, and is typically separated from other parts using p elements.
Putting this together, here is how one might ask for the customer's name:
<form>
<p><label>Customer name: <input></label></p>
</form>
To let the user select the size of the pizza, we can use a set of radio buttons. Radio buttons
also use the input element, this time with a type attribute with the value radio. To make the radio buttons work as a group, they are
given a common name using the name attribute. To group a batch
of controls together, such as, in this case, the radio buttons, one can use the
fieldset element. The title of such a group of controls is given by the first element
in the fieldset, which has to be a legend element.
<form>
<p><label>Customer name: <input></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size> Small </label></p>
<p><label> <input type=radio name=size> Medium </label></p>
<p><label> <input type=radio name=size> Large </label></p>
</fieldset>
</form>
Changes from the previous step are highlighted.
To pick toppings, we can use checkboxes. These use the input element with a type attribute with the value checkbox:
<form>
<p><label>Customer name: <input></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size> Small </label></p>
<p><label> <input type=radio name=size> Medium </label></p>
<p><label> <input type=radio name=size> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox> Bacon </label></p>
<p><label> <input type=checkbox> Extra Cheese </label></p>
<p><label> <input type=checkbox> Onion </label></p>
<p><label> <input type=checkbox> Mushroom </label></p>
</fieldset>
</form>
The pizzeria for which this form is being written is always making mistakes, so it needs a way
to contact the customer. For this purpose, we can use form controls specifically for telephone
numbers (input elements with their type
attribute set to tel) and e-mail addresses
(input elements with their type attribute set to
email):
<form>
<p><label>Customer name: <input></label></p>
<p><label>Telephone: <input type=tel></label></p>
<p><label>E-mail address: <input type=email></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size> Small </label></p>
<p><label> <input type=radio name=size> Medium </label></p>
<p><label> <input type=radio name=size> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox> Bacon </label></p>
<p><label> <input type=checkbox> Extra Cheese </label></p>
<p><label> <input type=checkbox> Onion </label></p>
<p><label> <input type=checkbox> Mushroom </label></p>
</fieldset>
</form>
We can use an input element with its type
attribute set to time to ask for a delivery time. Many
of these form controls have attributes to control exactly what values can be specified; in this
case, three attributes of particular interest are min, max, and step. These set the
minimum time, the maximum time, and the interval between allowed values (in seconds). This
pizzeria only delivers between 11am and 9pm, and doesn't promise anything better than 15 minute
increments, which we can mark up as follows:
<form>
<p><label>Customer name: <input></label></p>
<p><label>Telephone: <input type=tel></label></p>
<p><label>E-mail address: <input type=email></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size> Small </label></p>
<p><label> <input type=radio name=size> Medium </label></p>
<p><label> <input type=radio name=size> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox> Bacon </label></p>
<p><label> <input type=checkbox> Extra Cheese </label></p>
<p><label> <input type=checkbox> Onion </label></p>
<p><label> <input type=checkbox> Mushroom </label></p>
</fieldset>
<p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p>
</form>
The textarea element can be used to provide a free-form text field. In this
instance, we are going to use it to provide a space for the customer to give delivery
instructions:
<form>
<p><label>Customer name: <input></label></p>
<p><label>Telephone: <input type=tel></label></p>
<p><label>E-mail address: <input type=email></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size> Small </label></p>
<p><label> <input type=radio name=size> Medium </label></p>
<p><label> <input type=radio name=size> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox> Bacon </label></p>
<p><label> <input type=checkbox> Extra Cheese </label></p>
<p><label> <input type=checkbox> Onion </label></p>
<p><label> <input type=checkbox> Mushroom </label></p>
</fieldset>
<p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p>
<p><label>Delivery instructions: <textarea></textarea></label></p>
</form>
Finally, to make the form submittable we use the button element:
<form>
<p><label>Customer name: <input></label></p>
<p><label>Telephone: <input type=tel></label></p>
<p><label>E-mail address: <input type=email></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size> Small </label></p>
<p><label> <input type=radio name=size> Medium </label></p>
<p><label> <input type=radio name=size> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox> Bacon </label></p>
<p><label> <input type=checkbox> Extra Cheese </label></p>
<p><label> <input type=checkbox> Onion </label></p>
<p><label> <input type=checkbox> Mushroom </label></p>
</fieldset>
<p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p>
<p><label>Delivery instructions: <textarea></textarea></label></p>
<p><button>Submit order</button></p>
</form>
Implementing the server-side processing for a form
This section is non-normative.
The exact details for writing a server-side processor are out of scope for this specification.
For the purposes of this introduction, we will assume that the script at https://pizza.example.com/order.cgi is configured to accept submissions using the
application/x-www-form-urlencoded format,
expecting the following parameters sent in an HTTP POST body:
custname- Customer's name
custtel- Customer's telephone number
custemail- Customer's e-mail address
size- The pizza size, either
small, medium, or large topping- A topping, specified once for each selected topping, with the allowed values being
bacon, cheese, onion, and mushroom delivery- The requested delivery time
comments- The delivery instructions
Configuring a form to communicate with a server
This section is non-normative.
Form submissions are exposed to servers in a variety of ways, most commonly as HTTP GET or POST
requests. To specify the exact method used, the method
attribute is specified on the form element. This doesn't specify how the form data is
encoded, though; to specify that, you use the enctype
attribute. You also have to specify the URL of the service that will handle the
submitted data, using the action attribute.
For each form control you want submitted, you then have to give a name that will be used to
refer to the data in the submission. We already specified the name for the group of radio buttons;
the same attribute (name) also specifies the submission name.
Radio buttons can be distinguished from each other in the submission by giving them different
values, using the value attribute.
Multiple controls can have the same name; for example, here we give all the checkboxes the same
name, and the server distinguishes which checkbox was checked by seeing which values are submitted
with that name — like the radio buttons, they are also given unique values with the value attribute.
Given the settings in the previous section, this all becomes:
<form method="post"
enctype="application/x-www-form-urlencoded"
action="https://pizza.example.com/order.cgi">
<p><label>Customer name: <input name="custname"></label></p>
<p><label>Telephone: <input type=tel name="custtel"></label></p>
<p><label>E-mail address: <input type=email name="custemail"></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size value="small"> Small </label></p>
<p><label> <input type=radio name=size value="medium"> Medium </label></p>
<p><label> <input type=radio name=size value="large"> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p>
<p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p>
<p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p>
<p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p>
</fieldset>
<p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery"></label></p>
<p><label>Delivery instructions: <textarea name="comments"></textarea></label></p>
<p><button>Submit order</button></p>
</form>
There is no particular significance to the way some of the attributes have their
values quoted and others don't. The HTML syntax allows a variety of equally valid ways to specify
attributes, as discussed in the syntax section.
For example, if the customer entered "Denise Lawrence" as their name, "555-321-8642" as their
telephone number, did not specify an e-mail address, asked for a medium-sized pizza, selected the
Extra Cheese and Mushroom toppings, entered a delivery time of 7pm, and left the delivery
instructions text field blank, the user agent would submit the following to the online Web
service:
custname=Denise+Lawrence&custtel=555-321-8642&custemail=&size=medium&topping=cheese&topping=mushroom&delivery=19%3A00&comments=
Client-side form validation
This section is non-normative.
Forms can be annotated in such a way that the user agent will check the user's input before the
form is submitted. The server still has to verify the input is valid (since hostile users can
easily bypass the form validation), but it allows the user to avoid the wait incurred by having
the server be the sole checker of the user's input.
The simplest annotation is the required attribute,
which can be specified on input elements to indicate that the form is not to be
submitted until a value is given. By adding this attribute to the customer name, pizza size, and
delivery time fields, we allow the user agent to notify the user when the user submits the form
without filling in those fields:
<form method="post"
enctype="application/x-www-form-urlencoded"
action="https://pizza.example.com/order.cgi">
<p><label>Customer name: <input name="custname" required></label></p>
<p><label>Telephone: <input type=tel name="custtel"></label></p>
<p><label>E-mail address: <input type=email name="custemail"></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size required value="small"> Small </label></p>
<p><label> <input type=radio name=size required value="medium"> Medium </label></p>
<p><label> <input type=radio name=size required value="large"> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p>
<p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p>
<p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p>
<p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p>
</fieldset>
<p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p>
<p><label>Delivery instructions: <textarea name="comments"></textarea></label></p>
<p><button>Submit order</button></p>
</form>
It is also possible to limit the length of the input, using the maxlength attribute. By adding this to the textarea
element, we can limit users to 1000 characters, preventing them from writing huge essays to the
busy delivery drivers instead of staying focused and to the point:
<form method="post"
enctype="application/x-www-form-urlencoded"
action="https://pizza.example.com/order.cgi">
<p><label>Customer name: <input name="custname" required></label></p>
<p><label>Telephone: <input type=tel name="custtel"></label></p>
<p><label>E-mail address: <input type=email name="custemail"></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size required value="small"> Small </label></p>
<p><label> <input type=radio name=size required value="medium"> Medium </label></p>
<p><label> <input type=radio name=size required value="large"> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p>
<p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p>
<p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p>
<p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p>
</fieldset>
<p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p>
<p><label>Delivery instructions: <textarea name="comments" maxlength=1000></textarea></label></p>
<p><button>Submit order</button></p>
</form>
When a form is submitted, invalid events are
fired at each form control that is invalid, and then at the form element itself. This
can be useful for displaying a summary of the problems with the form, since typically the browser
itself will only report one problem at a time.
Enabling client-side automatic filling of form controls
This section is non-normative.
Some browsers attempt to aid the user by automatically filling form controls rather than having
the user reenter their information each time. For example, a field asking for the user's telephone
number can be automatically filled with the user's phone number.
To help the user agent with this, the autocomplete
attribute can be used to describe the field's purpose. In the case of this form, we have three
fields that can be usefully annotated in this way: the information about who the pizza is to be
delivered to. Adding this information looks like this:
<form method="post"
enctype="application/x-www-form-urlencoded"
action="https://pizza.example.com/order.cgi">
<p><label>Customer name: <input name="custname" required autocomplete="shipping name"></label></p>
<p><label>Telephone: <input type=tel name="custtel" autocomplete="shipping tel"></label></p>
<p><label>E-mail address: <input type=email name="custemail" autocomplete="shipping email"></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size required value="small"> Small </label></p>
<p><label> <input type=radio name=size required value="medium"> Medium </label></p>
<p><label> <input type=radio name=size required value="large"> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p>
<p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p>
<p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p>
<p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p>
</fieldset>
<p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p>
<p><label>Delivery instructions: <textarea name="comments" maxlength=1000></textarea></label></p>
<p><button>Submit order</button></p>
</form>
Improving the user experience on mobile devices
This section is non-normative.
Some devices, in particular those with on-screen keyboards and those in locales with languages
with many characters (e.g. Japanese), can provide the user with multiple input modalities. For
example, when typing in a credit card number the user may wish to only see keys for digits 0-9,
while when typing in their name they may wish to see a form field that by default capitalises each
word.
Using the inputmode attribute we can select appropriate
input modalities:
<form method="post"
enctype="application/x-www-form-urlencoded"
action="https://pizza.example.com/order.cgi">
<p><label>Customer name: <input name="custname" required autocomplete="shipping name" inputmode="latin-name"></label></p>
<p><label>Telephone: <input type=tel name="custtel" autocomplete="shipping tel"></label></p>
<p><label>E-mail address: <input type=email name="custemail" autocomplete="shipping email"></label></p>
<fieldset>
<legend> Pizza Size </legend>
<p><label> <input type=radio name=size required value="small"> Small </label></p>
<p><label> <input type=radio name=size required value="medium"> Medium </label></p>
<p><label> <input type=radio name=size required value="large"> Large </label></p>
</fieldset>
<fieldset>
<legend> Pizza Toppings </legend>
<p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p>
<p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p>
<p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p>
<p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p>
</fieldset>
<p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p>
<p><label>Delivery instructions: <textarea name="comments" maxlength=1000 inputmode="latin-prose"></textarea></label></p>
<p><button>Submit order</button></p>
</form>
The difference between the field type, the autofill field name, and the input modality
This section is non-normative.
The type, autocomplete, and inputmode attributes can seem confusingly similar. For instance,
in all three cases, the string "email" is a valid value. This section
attempts to illustrate the difference between the three attributes and provides advice suggesting
how to use them.
The type attribute on input elements decides
what kind of control the user agent will use to expose the field. Choosing between different
values of this attribute is the same choice as choosing whether to use an input
element, a textarea element, a select element, a keygen
element, etc.
The autocomplete attribute, in contrast, describes
what the value that the user will enter actually represents. Choosing between different values of
this attribute is the same choice as choosing what the label for the element will be.
First, consider telephone numbers. If a page is asking for a telephone number from the user,
the right form control to use is <input type=tel>.
However, which autocomplete value to use depends on
which phone number the page is asking for, whether they expect a telephone number in the
international format or just the local format, and so forth.
For example, a page that forms part of a checkout process on an e-commerce site for a customer
buying a gift to be shipped to a friend might need both the buyer's telephone number (in case of
payment issues) and the friend's telephone number (in case of delivery issues). If the site
expects international phone numbers (with the country code prefix), this could thus look like
this:
<p><label>Your phone number: <input type=tel name=custtel autocomplete="billing tel"></label>
<p><label>Recipient's phone number: <input type=tel name=shiptel autocomplete="shipping tel"></label>
<p>Please enter complete phone numbers including the country code prefix, as in "+1 555 123 4567".
But if the site only supports British customers and recipients, it might instead look like this
(notice the use of tel-national rather than
tel):
<p><label>Your phone number: <input type=tel name=custtel autocomplete="billing tel-national"></label>
<p><label>Recipient's phone number: <input type=tel name=shiptel autocomplete="shipping tel-national"></label>
<p>Please enter complete UK phone numbers, as in "(01632) 960 123".
Now, consider a person's preferred languages. The right autocomplete value is language. However, there could be a number of
different form controls used for the purpose: a free text field (<input type=text>), a drop-down list (<select>), radio buttons (<input
type=radio>), etc. It only depends on what kind of interface is desired.
The inputmode decides what kind of input modality (e.g.
keyboard) to use, when the control is a free-form text field.
Consider names. If a page just wants one name from the user, then the relevant control is <input type=text>. If the page is asking for the user's
full name, then the relevant autocomplete value is name. But if the user is Japanese, and the page is asking
for the user's Japanese name and the user's romanised name, then it would be helpful to the user
if the first field defaulted to a Japanese input modality, while the second defaulted to a Latin
input modality (ideally with automatic capitalization of each word). This is where the inputmode attribute can help:
<p><label>Japanese name: <input name="j" type="text" autocomplete="section-jp name" inputmode="kana"></label>
<label>Romanised name: <input name="e" type="text" autocomplete="section-en name" inputmode="latin-name"></label>
In this example, the "section-*" keywords in
the autocomplete attributes' values tell the user agent
that the two fields expect different names. Without them, the user agent could
automatically fill the second field with the value given in the first field when the user gave a
value to the first field.
The "-jp" and "-en" parts of the
keywords are opaque to the user agent; the user agent cannot guess, from those, that the two names
are expected to be in Japanese and English respectively.
Date, time, and number formats
This section is non-normative.
In this pizza delivery example, the times are specified in the format "HH:MM": two digits for
the hour, in 24-hour format, and two digits for the time. (Seconds could also be specified, though
they are not necessary in this example.)
In some locales, however, times are often expressed differently when presented to users. For
example, in the United States, it is still common to use the 12-hour clock with an am/pm
indicator, as in "2pm". In France, it is common to separate the hours from the minutes using an
"h" character, as in "14h00".
Similar issues exist with dates, with the added complication that even the order of the
components is not always consistent — for example, in Cyprus the first of February 2003
would typically be written "1/2/03", while that same date in Japan would typically be written as
"2003年02月01日" — and even with numbers, where locales differ, for
example, in what punctuation is used as the decimal separator and the thousands separator.
It is therefore important to distinguish the time, date, and number formats used in HTML and in
form submissions, which are always the formats defined in this specification (and based on the
well-established ISO 8601 standard for computer-readable date and time formats), from the time,
date, and number formats presented to the user by the browser and accepted as input from the user
by the browser.
The format used "on the wire", i.e. in HTML markup and in form submissions, is intended to be
computer-readable and consistent irrespective of the user's locale. Dates, for instance, are
always written in the format "YYYY-MM-DD", as in "2003-02-01". Users are not expected to ever see
this format.
The time, date, or number given by the page in the wire format is then translated to the user's
preferred presentation (based on user preferences or on the locale of the page itself), before
being displayed to the user. Similarly, after the user inputs a time, date, or number using their
preferred format, the user agent converts it back to the wire format before putting it in the DOM
or submitting it.
This allows scripts in pages and on servers to process times, dates, and numbers in a
consistent manner without needing to support dozens of different formats, while still supporting
the users' needs.
See also the implementation notes regarding
localization of form controls.
Categories
Mostly for historical reasons, elements in this section fall into several overlapping (but
subtly different) categories in addition to the usual ones like flow content,
phrasing content, and interactive content.
A number of the elements are form-associated
elements, which means they can have a form owner.
The form-associated elements fall into several
subcategories:
- Listed elements
-
Denotes elements that are listed in the form.elements and fieldset.elements APIs.
- Submittable elements
-
Denotes elements that can be used for constructing the
form data set when a form element is submitted.
Some submittable elements can be, depending on their
attributes, buttons. The prose below defines when an element
is a button. Some buttons are specifically submit
buttons.
- Resettable elements
-
Denotes elements that can be affected when a form element is reset.
- Reassociateable elements
-
Denotes elements that have a form content attribute, and a
matching form IDL attribute, that allow authors to specify an
explicit form owner.
Some elements, not all of them form-associated,
are categorised as labelable elements. These are elements that
can be associated with a label element.
The form element
- Categories:
- Flow content.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Flow content, but with no
form element descendants. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
accept-charset — Character encodings to use for form submissionaction — URL to use for form submissionautocomplete — Default setting for autofill feature for controls in the formenctype — Form data set encoding type to use for form submissionmethod — HTTP method to use for form submissionname — Name of form to use in the document.forms APInovalidate — Bypass form control validation for form submissiontarget — Browsing context for form submission- Allowed ARIA role attribute values:
- Any role value.
- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
[OverrideBuiltins]
interface HTMLFormElement : HTMLElement {
attribute DOMString acceptCharset;
attribute DOMString action;
attribute DOMString autocomplete;
attribute DOMString enctype;
attribute DOMString encoding;
attribute DOMString method;
attribute DOMString name;
attribute boolean noValidate;
attribute DOMString target;
readonly attribute HTMLFormControlsCollection elements;
readonly attribute long length;
getter Element (unsigned long index);
getter (RadioNodeList or Element) (DOMString name);
void submit();
void reset();
boolean checkValidity();
boolean reportValidity();
void requestAutocomplete();
};
The form element represents a collection of form-associated elements, some of which can represent
editable values that can be submitted to a server for processing.
The accept-charset attribute gives the
character encodings that are to be used for the submission. If specified, the value must be an
ordered set of unique space-separated tokens that are ASCII
case-insensitive, and each token must be an ASCII case-insensitive match for
one of the labels of an ASCII-compatible character
encoding. [[!ENCODING]]
The name attribute represents the
form's name within the forms collection. The
value must not be the empty string, and the value must be unique amongst the form
elements in the forms collection that it is in, if
any.
The autocomplete attribute is an
enumerated attribute. The attribute has two states. The on keyword maps to the on state, and the off keyword maps to the off state. The attribute may also be omitted. The
missing value default is the on state. The off state indicates that by default, form
controls in the form will have their autofill field name set to "off"; the on state indicates that by default, form controls
in the form will have their autofill field name set to "on".
The action, enctype,
method, novalidate,
and target attributes are attributes for form
submission.
- form .
elements -
Returns an HTMLFormControlsCollection of the form controls in the form (excluding image
buttons for historical reasons).
- form .
length -
Returns the number of form controls in the form (excluding image buttons for historical
reasons).
- form[index]
-
Returns the indexth element in the form (excluding image buttons for
historical reasons).
- form[name]
-
Returns the form control (or, if there are several, a RadioNodeList of the form
controls) in the form with the given ID or name (excluding image buttons for historical reasons); or, if there
are none, returns the img element with the given ID.
Once an element has been referenced using a particular name, that name will continue being
available as a way to reference that element in this method, even if the element's actual ID or name changes, for as long as
the element remains in the Document.
If there are multiple matching items, then a RadioNodeList object containing all
those elements is returned.
- form .
submit() -
Submits the form.
- form .
reset() -
Resets the form.
- form .
checkValidity() -
Returns true if the form's controls are all valid; otherwise, returns false.
- form .
reportValidity() -
Returns true if the form's controls are all valid; otherwise, returns false and informs the user.
- form .
requestAutocomplete() -
Triggers a user-agent-specific user interface to help the user fill in any
fields that have an autofill field name other than "on" or "off".
The form element will subsequently receive an event, either autocomplete, indicating that the fields have been prefilled,
or autocompleteerror (using the
AutocompleteErrorEvent interface), indicating that there was some problem (the
general class of problem is described by the reason IDL attribute on the event).
The autocomplete IDL attribute must
reflect the content attribute of the same name, limited to only known
values.
The requestAutocomplete() method is part of
the autofill mechanism.
The name IDL attribute must reflect
the content attribute of the same name.
The acceptCharset IDL attribute must
reflect the accept-charset content
attribute.
The elements IDL attribute must return an
HTMLFormControlsCollection rooted at the form element's home
subtree's root element, whose filter matches listed elements whose form owner is the
form element, with the exception of input elements whose type attribute is in the Image Button state, which must, for historical reasons, be
excluded from this particular collection.
The length IDL attribute must return the number
of nodes represented by the elements collection.
The supported property indices at any instant are the indices supported by the
object returned by the elements attribute at that
instant.
When a form element is indexed for indexed property
retrieval, the user agent must return the value returned by the item method on the elements collection, when invoked with the given index as its
argument.
Each form element has a mapping of names to elements called the past names
map. It is used to persist names of controls even when they change names.
The supported property names consist of the names obtained from the following
algorithm, in the order obtained from this algorithm:
Let sourced names be an initially empty ordered list of tuples
consisting of a string, an element, a source, where the source is either id, name,
or past, and, if the source is past, an age.
-
For each listed element candidate
whose form owner is the form element, with the exception of any
input elements whose type attribute is in the
Image Button state, run these substeps:
If candidate has an id attribute, add
an entry to sourced names with that id
attribute's value as the string, candidate as the element, and id as
the source.
If candidate has a name attribute,
add an entry to sourced names with that name attribute's value as the string, candidate
as the element, and name as the source.
-
For each img element candidate whose form owner
is the form element, run these substeps:
If candidate has an id attribute, add
an entry to sourced names with that id
attribute's value as the string, candidate as the element, and id as
the source.
If candidate has a name attribute,
add an entry to sourced names with that name attribute's value as the string, candidate
as the element, and name as the source.
-
For each entry past entry in the past names map add an entry
to sourced names with the past entry's name as the
string, past entry's element as the element, past as the source, and
the length of time past entry has been in the past names map as
the age.
Sort sourced names by tree order of the element entry of
each tuple, sorting entries with the same element by putting entries whose source is id
first, then entries whose source is name, and finally entries whose source is past,
and sorting entries with the same element and source by their age, oldest first.
Remove any entries in sourced names that have the empty string as
their name.
Remove any entries in sourced names that have the same name as an
earlier entry in the map.
Return the list of names from sourced names, maintaining their
relative order.
The properties exposed in this way must be unenumerable.
When a form element is indexed for named property
retrieval, the user agent must run the following steps:
Let candidates be a live RadioNodeList
object containing all the listed elements whose form
owner is the form element that have either an id
attribute or a name attribute equal to name, with the exception of input elements whose type attribute is in the Image
Button state, in tree order.
If candidates is empty, let candidates be a
live RadioNodeList object containing all the img elements
that are descendants of the form element and that have either an id attribute or a name attribute equal
to name, in tree order.
If candidates is empty, name is the name of one of
the entries in the form element's past names map: return the object
associated with name in that map.
If candidates contains more than one node, return candidates and abort these steps.
Otherwise, candidates contains exactly one node. Add a mapping from
name to the node in candidates in the form
element's past names map, replacing the previous entry with the same name, if
any.
Return the node in candidates.
If an element listed in a form element's past names map changes
form owner, then its entries must be removed from that map.
The submit() method, when invoked, must submit the form element from the form
element itself, with the submitted from submit() method flag set.
The reset() method, when invoked, must run the
following steps:
If the form element is marked as locked for reset, then abort these
steps.
Mark the form element as locked for reset.
Reset the form element.
Unmark the form element as locked for reset.
If the checkValidity() method is
invoked, the user agent must statically validate the constraints of the
form element, and return true if the constraint validation return a positive
result, and false if it returned a negative result.
If the reportValidity() method is
invoked, the user agent must interactively validate the constraints of the
form element, and return true if the constraint validation return a positive
result, and false if it returned a negative result.
This example shows two search forms:
<form action="http://www.google.com/search" method="get">
<label>Google: <input type="search" name="q"></label> <input type="submit" value="Search...">
</form>
<form action="http://www.bing.com/search" method="get">
<label>Bing: <input type="search" name="q"></label> <input type="submit" value="Search...">
</form>
The label element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- Reassociateable form-associated element.
- Palpable content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but with no descendant labelable elements unless it is the element's labeled control, and no descendant
label elements. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
form — Associates the control with a form elementfor — Associate the label with form control- Allowed ARIA role attribute values:
- None
- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLLabelElement : HTMLElement {
readonly attribute HTMLFormElement? form;
attribute DOMString htmlFor;
readonly attribute HTMLElement? control;
};
The label element represents a caption in a user interface. The
caption can be associated with a specific form control, known as the
label element's labeled control, either using the for attribute, or by putting the form control inside the
label element itself.
Except where otherwise specified by the following rules, a label element has no
labeled control.
The for attribute may be specified to indicate a
form control with which the caption is to be associated. If the attribute is specified, the
attribute's value must be the ID of a labelable element in the same Document as the
label element. If the attribute is specified and there is an
element in the Document whose ID is equal to the
value of the for attribute, and the first such element is a
labelable element, then that element is the label
element's labeled control.
If the for attribute is not specified, but the
label element has a labelable element descendant,
then the first such descendant in tree order is the label element's
labeled control.
The label element's exact default presentation and behaviour, in particular what
its activation behaviour might be, if anything, should match the platform's label
behaviour. The activation behaviour of a label element for events targeted
at interactive content descendants of a label element, and any
descendants of those interactive content descendants, must be to do nothing.
For example, on platforms where clicking a checkbox label checks the checkbox, clicking the
label in the following snippet could trigger the user agent to run synthetic
click activation steps on the input element, as if the element itself had
been triggered by the user:
<label><input type=checkbox name=lost> Lost</label>
On other platforms, the behaviour might be just to focus the control, or do nothing.
Note: The ability to click or press a label to trigger an event on a control provides
usability and accessibility benefits by increasing the hit area of a control, making it easier for a user to operate.
These benefits may be lost or reduced, if the label element contains an element with its own activation
behavior, such as a link:
<!-- bad example - link inside label reduces checkbox activation area -->
<label><input type=checkbox name=tac>I agree to <a href="tandc.html">the terms and conditions</a></label>
<!-- bad example - all label text inside the link reduces activation area to checkbox only -->
<label><input type=checkbox name=tac><a href="tandc.html">I agree to the terms and conditions</a></label>
The usability and accessibility benefits can be maintained by placing such elements outside the label element:
<!-- good example - link outside label means checkbox activation area includes the checkbox and all the label text -->
<label><input type=checkbox name=tac>I agree to the terms and conditions</label>
(read <a href="tandc.html">Terms and Conditions</a>)
The form attribute is used to explicitly associate the
label element with its form owner.
The following example shows three form controls each with a label, two of which have small
text showing the right format for users to use.
<p><label>Full name: <input name=fn> <small>Format: First Last</small></label></p>
<p><label>Age: <input name=age type=number min=0></label></p>
<p><label>Post code: <input name=pc> <small>Format: AB12 3CD</small></label></p>
- label .
control -
Returns the form control that is associated with this element.
The htmlFor IDL attribute must
reflect the for content attribute.
The control IDL attribute must return the
label element's labeled control, if any, or null if there isn't one.
The form IDL attribute is part of the element's forms
API.
- control .
labels -
Returns a NodeList of all the label elements that the form control
is associated with.
Labelable elements have a NodeList object
associated with them that represents the list of label elements, in tree
order, whose labeled control is the element in question. The labels IDL attribute of labelable elements, on getting, must return that
NodeList object.
The input element
- Categories:
- Flow content.
- Phrasing content.
- If the
type attribute is not in the Hidden state: Interactive content. - If the
type attribute is not in the Hidden state: Listed, labelable, submittable, resettable, and reassociateable form-associated element. - If the
type attribute is in the Hidden state: Listed, submittable, resettable, and reassociateable form-associated element. - If the
type attribute is not in the Hidden state: Palpable content. - Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
accept — Hint for expected file type in file upload controlsalt — Replacement text for use when images are not availableautocomplete — Hint for form autofill featureautofocus — Automatically focus the form control when the page is loadedchecked — Whether the command or control is checkeddirname — Name of form field to use for sending the element's directionality in form submissiondisabled — Whether the form control is disabledform — Associates the control with a form elementformaction — URL to use for form submissionformenctype — Form data set encoding type to use for form submissionformmethod — HTTP method to use for form submissionformnovalidate — Bypass form control validation for form submissionformtarget — Browsing context for form submissionheight — Vertical dimensioninputmode — Hint for selecting an input modalitylist — List of autocomplete optionsmax — Maximum valuemaxlength — Maximum length of valuemin — Minimum valueminlength — Minimum length of valuemultiple — Whether to allow multiple valuesname — Name of form control to use for form submission and in the form.elements API pattern — Pattern to be matched by the form control's valueplaceholder — User-visible label to be placed within the form controlreadonly — Whether to allow the value to be edited by the userrequired — Whether the control is required for form submissionsize — Size of the controlsrc — Address of the resourcestep — Granularity to be matched by the form control's valuetype — Type of form controlvalue — Value of the form controlwidth — Horizontal dimension- Also, the
title attribute has special semantics on this element: Description of pattern (when used with pattern attribute). - Allowed ARIA role attribute values:
- Depends upon state of the
type attribute. - Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
interface HTMLInputElement : HTMLElement {
attribute DOMString accept;
attribute DOMString alt;
attribute DOMString autocomplete;
attribute boolean autofocus;
attribute boolean defaultChecked;
attribute boolean checked;
attribute DOMString dirName;
attribute boolean disabled;
readonly attribute HTMLFormElement? form;
readonly attribute FileList? files;
attribute DOMString formAction;
attribute DOMString formEnctype;
attribute DOMString formMethod;
attribute boolean formNoValidate;
attribute DOMString formTarget;
attribute unsigned long height;
attribute boolean indeterminate;
attribute DOMString inputMode;
readonly attribute HTMLElement? list;
attribute DOMString max;
attribute long maxLength;
attribute DOMString min;
attribute long minLength;
attribute boolean multiple;
attribute DOMString name;
attribute DOMString pattern;
attribute DOMString placeholder;
attribute boolean readOnly;
attribute boolean required;
attribute unsigned long size;
attribute DOMString src;
attribute DOMString step;
attribute DOMString type;
attribute DOMString defaultValue;
[TreatNullAs=EmptyString] attribute DOMString value;
attribute Date? valueAsDate;
attribute unrestricted double valueAsNumber;
attribute double valueLow;
attribute double valueHigh;
attribute unsigned long width;
void stepUp(optional long n = 1);
void stepDown(optional long n = 1);
readonly attribute boolean willValidate;
readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
boolean reportValidity();
void setCustomValidity(DOMString error);
readonly attribute NodeList labels;
void select();
attribute unsigned long selectionStart;
attribute unsigned long selectionEnd;
attribute DOMString selectionDirection;
void setRangeText(DOMString replacement);
void setRangeText(DOMString replacement, unsigned long start, unsigned long end, optional SelectionMode selectionMode = "preserve");
void setSelectionRange(unsigned long start, unsigned long end, optional DOMString direction);
// also has obsolete members
};
The input element represents a typed data field, usually with a form
control to allow the user to edit the data.
The type attribute controls the data type (and
associated control) of the element. It is an enumerated attribute. The following
table lists the keywords and states for the attribute — the keywords in the left column map
to the states in the cell in the second column on the same row as the keyword.
The missing value default is the Text
state.
Which of the
accept,
alt,
autocomplete,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
list,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
required,
size,
src,
step, and
width content attributes, the
checked,
files,
valueAsDate,
valueAsNumber,
valueLow,
valueHigh, and
list IDL attributes, the
select() method, the
selectionStart,
selectionEnd, and
selectionDirection, IDL attributes, the
setRangeText() and
setSelectionRange() methods, the
stepUp() and
stepDown() methods, and the
input and
change events apply to an
input element depends on the state of its
type attribute.
The subsections that define each type also clearly define in normative "bookkeeping" sections
which of these feature apply, and which do not apply, to each type. The behaviour of
these features depends on whether they apply or not, as defined in their various sections (q.v.
for content attributes, for APIs, for events).
The following table is non-normative and summarizes which of those
content attributes, IDL attributes, methods, and events apply to each state:
* If the multiple attribute
is not specified.
** If the multiple attribute
is specified.
Some states of the type attribute define a value
sanitization algorithm.
Each input element has a value, which is
exposed by the value IDL attribute. Some states define an
algorithm to convert a string to a number,
an algorithm to convert a number to a
string, an algorithm to convert a string to a
Date object, and an algorithm to
convert a Date object to a string, which are used by max, min, step, valueAsDate,
valueAsNumber, valueLow, valueHigh,
stepDown(), and stepUp().
Each input element has a boolean dirty
value flag. The dirty value flag must be
initially set to false when the element is created, and must be set to true whenever the user
interacts with the control in a way that changes the value.
(It is also set to true when the value is programmatically changed, as described in the definition
of the value IDL attribute.)
The value content attribute gives the default
value of the input element. When the value content attribute is added, set,
or removed, if the control's dirty value flag
is false, the user agent must set the value of the element
to the value of the value content attribute, if there is
one, or the empty string otherwise, and then run the current value sanitization
algorithm, if one is defined.
Each input element has a checkedness,
which is exposed by the checked IDL attribute.
Each input element has a boolean dirty checkedness flag. When it is true, the
element is said to have a dirty checkedness.
The dirty checkedness flag must be initially
set to false when the element is created, and must be set to true whenever the user interacts with
the control in a way that changes the checkedness.
The checked content attribute is a
boolean attribute that gives the default checkedness of the input element. When the checked content attribute is added,
if the control does not have dirty checkedness, the
user agent must set the checkedness of the element to
true; when the checked content attribute is removed, if
the control does not have dirty checkedness, the user
agent must set the checkedness of the element to
false.
The reset algorithm for input
elements is to set the dirty value flag and
dirty checkedness flag back to false, set
the value of the element to the value of the value content attribute, if there is one, or the empty string
otherwise, set the checkedness of the element to true if
the element has a checked content attribute and false if
it does not, empty the list of selected
files, and then invoke the value sanitization algorithm, if the type attribute's current state defines one.
Each input element can be mutable. Except where
otherwise specified, an input element is always mutable. Similarly, except where otherwise specified, the user
agent should not allow the user to modify the element's value or checkedness.
When an input element is disabled, it is not mutable.
The readonly attribute can also in some
cases (e.g. for the Date state, but not the Checkbox state) stop an input element from
being mutable.
The cloning steps for input elements
must propagate the value, dirty value flag, checkedness, and dirty checkedness flag from the node being cloned
to the copy.
When an input element is first created, the element's rendering and behaviour must
be set to the rendering and behaviour defined for the type
attribute's state, and the value sanitization algorithm, if one is defined for the
type attribute's state, must be invoked.
The name attribute represents the element's name.
The dirname attribute controls how the element's directionality is submitted.
The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted.
The form attribute is used to explicitly associate the input element with its form owner.
The autofocus attribute controls focus.
The inputmode attribute controls the user interface's input modality for the control.
The autocomplete attribute controls how the user agent provides autofill behaviour.
The indeterminate IDL attribute must
initially be set to false. On getting, it must return the last value it was set to. On setting, it
must be set to the new value. It has no effect except for changing the appearance of checkbox controls.
The accept, alt, max,
min, multiple, pattern, placeholder, required, size, src,
and step IDL attributes must reflect
the respective content attributes of the same name. The dirName IDL attribute must reflect the
dirname content attribute. The readOnly IDL attribute must reflect the
readonly content attribute. The defaultChecked IDL attribute must
reflect the checked content attribute. The
defaultValue IDL attribute must
reflect the value content attribute.
The type IDL attribute must reflect
the respective content attribute of the same name, limited to only known values. The
inputMode IDL attribute must
reflect the inputmode content attribute,
limited to only known values. The maxLength IDL attribute must reflect
the maxlength content attribute, limited to only
non-negative numbers. The minLength IDL attribute must reflect
the minlength content attribute, limited to only
non-negative numbers.
The IDL attributes width and height must return the rendered width and height of
the image, in CSS pixels, if an image is being rendered, and is being rendered to a
visual medium; or else the intrinsic width and height of the image, in CSS pixels, if an image is
available but not being rendered to a visual medium; or else 0,
if no image is available. When the input element's
type attribute is not in the Image Button state, then no image is available. [[!CSS]]
On setting, they must act as if they reflected the respective
content attributes of the same name.
The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the
constraint validation API. The labels IDL
attribute provides a list of the element's labels. The select(), selectionStart, selectionEnd, selectionDirection, setRangeText(), and setSelectionRange() methods and IDL attributes
expose the element's text selection. The autofocus, disabled, form, and name IDL attributes are part of the element's forms API.
States of the type attribute
Hidden state (type=hidden)
When an input element's type attribute is in
the Hidden state, the rules in this section apply.
The input element represents a value that is not intended to be
examined or manipulated by the user.
Constraint validation: If an input element's type attribute is in the Hidden state, it is barred from constraint
validation.
If the name attribute is present and has a value that is a
case-sensitive match for the string "_charset_", then the element's value attribute must be omitted.
The
autocomplete
content attribute applies to this element.
The
value
IDL attribute applies to this element and is
in mode default.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
list,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
required,
size,
src,
step, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
files,
list,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
select(),
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
The input and change events do not apply.
Text (type=text) state and Search state (type=search)
When an input element's type attribute is in
the Text state or the Search state, the rules in this section apply.
The input element represents a one line plain text edit control for
the element's value.
The difference between the Text state
and the Search state is primarily stylistic: on
platforms where search fields are distinguished from regular text fields, the Search state might result in an appearance consistent with
the platform's search fields rather than appearing like a regular text field.
If the element is mutable, its value should be editable by the user. User agents must not allow
users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the element's
value.
If the element is mutable, the user agent should allow the
user to change the writing direction of the element, setting it either to a left-to-right writing
direction or a right-to-left writing direction. If the user does so, the user agent must then run
the following steps:
Set the element's dir attribute to "ltr" if the user selected a left-to-right writing direction, and
"rtl" if the user selected a right-to-left writing
direction.
Queue a task to fire a simple event that bubbles named input at the input element.
The value attribute, if specified, must have a value that
contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line
breaks from the value.
The following common input element content
attributes, IDL attributes, and methods apply to the element:
autocomplete,
dirname,
inputmode,
list,
maxlength,
minlength,
pattern,
placeholder,
readonly,
required, and
size content attributes;
list,
selectionStart,
selectionEnd,
selectionDirection, and
value IDL attributes;
select(),
setRangeText(), and
setSelectionRange() methods.
The value IDL attribute is
in mode value.
The input and change events apply.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
max,
min,
multiple,
src,
step, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
files,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
stepDown() and
stepUp() methods.
Telephone state (type=tel)
When an input element's type attribute is in
the Telephone state, the rules in this section apply.
The input element represents a control for editing a telephone number
given in the element's value.
If the element is mutable, its value should be editable by the user. User agents may change the
spacing and, with care, the punctuation of values that the
user enters. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE
RETURN (CR) characters into the element's value.
The value attribute, if specified, must have a value that
contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line
breaks from the value.
Unlike the URL and E-mail types, the Telephone type does not enforce a particular syntax. This is
intentional; in practice, telephone number fields tend to be free-form fields, because there are a
wide variety of valid phone numbers. Systems that need to enforce a particular format are
encouraged to use the pattern attribute or the setCustomValidity() method to hook into the client-side
validation mechanism.
The following common input element content
attributes, IDL attributes, and methods apply to the element:
autocomplete,
list,
maxlength,
minlength,
pattern,
placeholder,
readonly,
required, and
size content attributes;
list,
selectionStart,
selectionEnd,
selectionDirection, and
value IDL attributes;
select(),
setRangeText(), and
setSelectionRange() methods.
The value IDL attribute is
in mode value.
The input and change events apply.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
max,
min,
multiple,
src,
step, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
files,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
stepDown() and
stepUp() methods.
URL state (type=url)
When an input element's type attribute is in
the URL state, the rules in this section apply.
The input element represents a control for editing a single
absolute URL given in the element's value.
If the element is mutable, the user agent should allow the
user to change the URL represented by its value. User agents
may allow the user to set the value to a string that is not
a valid absolute URL, but may also or instead
automatically escape characters entered by the user so that the value is always a valid
absolute URL (even if that isn't the actual value seen and edited by the user in the
interface). User agents should allow the user to set the value to the empty string. User agents must not allow users to
insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value.
The value attribute, if specified and not empty, must
have a value that is a valid URL potentially surrounded by spaces that is also an
absolute URL.
The value sanitization algorithm is as follows: Strip line
breaks from the value, then strip leading and
trailing whitespace from the value.
Constraint validation: While the value
of the element is neither the empty string nor a valid
absolute URL, the element is suffering from a type mismatch.
The following common input element content
attributes, IDL attributes, and methods apply to the element:
autocomplete,
list,
maxlength,
minlength,
pattern,
placeholder,
readonly,
required, and
size content attributes;
list,
selectionStart,
selectionEnd,
selectionDirection, and
value IDL attributes;
select(),
setRangeText(), and
setSelectionRange() methods.
The value IDL attribute is
in mode value.
The input and change events apply.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
max,
min,
multiple,
src,
step, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
files,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
stepDown() and
stepUp() methods.
If a document contained the following markup:
<input type="url" name="location" list="urls">
<datalist id="urls">
<option label="MIME: Format of Internet Message Bodies" value="http://tools.ietf.org/html/rfc2045">
<option label="HTML 4.01 Specification" value="http://www.w3.org/TR/html4/">
<option label="Form Controls" value="http://www.w3.org/TR/xforms/slice8.html#ui-commonelems-hint">
<option label="Scalable Vector Graphics (SVG) 1.1 Specification" value="http://www.w3.org/TR/SVG/">
<option label="Feature Sets - SVG 1.1 - 20030114" value="http://www.w3.org/TR/SVG/feature.html">
<option label="The Single UNIX Specification, Version 3" value="http://www.unix-systems.org/version3/">
</datalist>
...and the user had typed "www.w3", and the user agent had also found that the user
had visited http://www.w3.org/Consortium/#membership and http://www.w3.org/TR/XForms/ in the recent past, then the rendering might look
like this:
The first four URLs in this sample consist of the four URLs in the author-specified list that
match the text the user has entered, sorted in some UA-defined manner (maybe by how frequently
the user refers to those URLs). Note how the UA is using the knowledge that the values are URLs
to allow the user to omit the scheme part and perform intelligent matching on the domain
name.
The last two URLs (and probably many more, given the scrollbar's indications of more values
being available) are the matches from the user agent's session history data. This data is not
made available to the page DOM. In this particular case, the UA has no titles to provide for
those values.
E-mail state (type=email)
When an input element's type attribute is in
the E-mail state, the rules in this section apply.
How the E-mail state operates depends on whether the
multiple attribute is specified or not.
- When the
multiple attribute is not specified on the
element -
The input element represents a control for editing an e-mail
address given in the element's value.
If the element is mutable, the user agent should allow the
user to change the e-mail address represented by its value. User agents may allow the user to set the value to a string that is not a valid e-mail
address. The user agent should act in a manner consistent with expecting the user to
provide a single e-mail address. User agents should allow the user to set the value to the empty string. User agents must not allow users to
insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value. User agents may transform the value for display and editing; in particular, user agents should
convert punycode in the domain labels of the value to IDN in the display and
vice versa.
Constraint validation: While the user interface is representing input that
the user agent cannot convert to punycode, the control is suffering from bad
input.
The value attribute, if specified and not empty, must
have a value that is a single valid e-mail address.
The value sanitization algorithm is as follows: Strip
line breaks from the value, then strip
leading and trailing whitespace from the value.
Constraint validation: While the value
of the element is neither the empty string nor a single valid e-mail address, the
element is suffering from a type mismatch.
- When the
multiple attribute is specified on
the element -
The input element represents a control for adding, removing, and
editing the e-mail addresses given in the element's values.
If the element is mutable, the user agent should allow the
user to add, remove, and edit the e-mail addresses represented by its values. User agents may allow the user to set any
individual value in the list of values to a
string that is not a valid e-mail address, but must not allow users to set any
individual value to a string containing U+002C COMMA (,), U+000A LINE FEED (LF), or U+000D
CARRIAGE RETURN (CR) characters. User agents should allow the user to remove all the addresses
in the element's values. User agents may
transform the values for display and editing; in
particular, user agents should convert punycode in the domain labels of the value to IDN in the display and vice versa.
Constraint validation: While the user interface describes a situation where
an individual value contains a U+002C COMMA (,) or is representing input that the user agent
cannot convert to punycode, the control is suffering from bad input.
Whenever the user changes the element's values, the user agent must run the following
steps:
Let latest values be a copy of the element's values.
Strip leading and trailing whitespace from each value in latest values.
Let the element's value be the result of
concatenating all the values in latest values, separating each value from
the next by a single U+002C COMMA character (,), maintaining the list's order.
The value attribute, if specified, must have a value
that is a valid e-mail address list.
The value sanitization algorithm is as follows:
Split on commas the element's value, strip leading and trailing whitespace from
each resulting token, if any, and let the element's values be the (possibly empty) resulting list of
(possibly empty) tokens, maintaining the original order.
Let the element's value be the result of
concatenating the element's values, separating
each value from the next by a single U+002C COMMA character (,), maintaining the list's
order.
Constraint validation: While the value
of the element is not a valid e-mail address list, the element is suffering
from a type mismatch.
When the multiple attribute is set or removed, the
user agent must run the value sanitization algorithm.
A valid e-mail address is a string that matches the email
production of the following ABNF, the character set for which is Unicode. This ABNF implements the
extensions described in RFC 1123. [[!ABNF]] [[!RFC5322]] [[!RFC1034]] [[!RFC1123]]
email = 1*( atext / "." ) "@" label *( "." label )
label = let-dig [ [ ldh-str ] let-dig ] ; limited to a length of 63 characters by RFC 1034 section 3.5
atext = < as defined in RFC 5322 section 3.2.3 >
let-dig = < as defined in RFC 1034 section 3.5 >
ldh-str = < as defined in RFC 1034 section 3.5 >
This requirement is a willful violation of RFC 5322, which defines a
syntax for e-mail addresses that is simultaneously too strict (before the "@" character), too
vague (after the "@" character), and too lax (allowing comments, whitespace characters, and quoted
strings in manners unfamiliar to most users) to be of practical use here.
The following JavaScript- and Perl-compatible regular expression is an implementation of the
above definition.
/^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/
A valid e-mail address list is a set of comma-separated tokens, where
each token is itself a valid e-mail address. To obtain the list of
tokens from a valid e-mail address list, and implementation must split the string on commas.
The following common input element content
attributes, IDL attributes, and methods apply to the element:
autocomplete,
list,
maxlength,
minlength,
multiple,
pattern,
placeholder,
readonly,
required, and
size content attributes;
list and
value IDL attributes;
select() method.
The value IDL attribute is
in mode value.
The input and change events apply.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
max,
min,
src,
step, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
files,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
setRangeText(),
setSelectionRange(),
stepDown() and
stepUp() methods.
Password state (type=password)
When an input element's type attribute is in
the Password state, the rules in this section
apply.
The input element represents a one line plain text edit control for
the element's value. The user agent should obscure the value
so that people other than the user cannot see it.
If the element is mutable, its value should be editable by the user. User agents must not allow
users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value.
The value attribute, if specified, must have a value that
contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line
breaks from the value.
The following common input element content
attributes, IDL attributes, and methods apply to the element:
autocomplete,
inputmode,
maxlength,
minlength,
pattern,
placeholder,
readonly,
required, and
size content attributes;
selectionStart,
selectionEnd,
selectionDirection, and
value IDL attributes;
select(),
setRangeText(), and
setSelectionRange() methods.
The value IDL attribute is
in mode value.
The input and change events apply.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
list,
max,
min,
multiple,
src,
step, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
files,
list,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
stepDown() and
stepUp() methods.
Date and Time state (type=datetime)
When an input element's type attribute is in
the Date and Time state, the rules in this section
apply.
The input element represents a control for setting the element's
value to a string representing a specific global date and time. User agents may display
the date and time in whatever time zone is appropriate for the user.
If the element is mutable, the user agent should allow the
user to change the global date and time represented by its
value, as obtained by parsing a global date and time from it. User agents must not allow the user to
set the value to a non-empty string that is not a
valid normalised forced-UTC global date and time string, though user agents may allow
the user to set and view the time in another time zone and silently translate the time to and from
the UTC time zone in the value. If the user agent provides a
user interface for selecting a global date and time, then
the value must be set to a valid normalised forced-UTC
global date and time string representing the user's selection. User agents should allow the
user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user
agent cannot convert to a valid normalised forced-UTC global date and time string,
the control is suffering from bad input.
See the introduction section for a discussion of
the difference between the input format and submission format for date, time, and number form
controls, and the implementation notes
regarding localization of form controls.
The value attribute, if specified and not empty, must
have a value that is a valid global date and time string.
The value sanitization algorithm is as follows: If the value of the element is a valid global date and time
string, then adjust the time so that the value
represents the same point in time but expressed in the UTC time zone as a valid normalized
forced-UTC global date and time string, otherwise, set it to the empty string instead.
The min attribute, if specified, must have a value that is
a valid global date and time string. The max
attribute, if specified, must have a value that is a valid global date and time
string.
The step attribute is expressed in seconds. The step scale factor is 1000 (which
converts the seconds to milliseconds, as used in the other algorithms). The default step is 60 seconds.
When the element is suffering from a step mismatch, the user agent may round the
element's value to the nearest global date and time for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a global date and time from input results in an error, then return an error; otherwise, return the number of
milliseconds elapsed from midnight UTC on the morning of 1970-01-01 (the time represented by the
value "1970-01-01T00:00:00.0Z") to the parsed global date and time, ignoring leap seconds.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a
valid normalised forced-UTC global date and time string that represents the global date and time that is input
milliseconds after midnight UTC on the morning of 1970-01-01 (the time represented by the value
"1970-01-01T00:00:00.0Z").
The algorithm to convert a string to a
Date object, given a string input, is as follows:
If parsing a global date and time from
input results in an error, then return an error; otherwise, return a new Date object representing the parsed global date and time, expressed in UTC.
The algorithm to convert a
Date object to a string, given a Date object input, is as follows: Return a valid normalised forced-UTC global
date and time string that represents the global date and
time that is represented by input.
The Date and Time state (and other date- and
time-related states described in subsequent sections) is not intended for the entry of values for
which a precise date and time relative to the contemporary calendar cannot be established. For
example, it would be inappropriate for the entry of times like "one millisecond after the big
bang", "the early part of the Jurassic period", or "a winter around 250 BCE".
For the input of dates before the introduction of the Gregorian calendar, authors are
encouraged to not use the Date and Time state (and
the other date- and time-related states described in subsequent sections), as user agents are not
required to support converting dates and times from earlier periods to the Gregorian calendar,
and asking users to do so manually puts an undue burden on users. (This is complicated by the
manner in which the Gregorian calendar was phased in, which occurred at different times in
different countries, ranging from partway through the 16th century all the way to early in the
20th.) Instead, authors are encouraged to provide fine-grained input controls using the
select element and input elements with the Number state.
The following common input element content
attributes, IDL attributes, and methods apply to the element:
autocomplete,
list,
max,
min,
readonly,
required, and
step content attributes;
list,
value,
valueAsDate, and
valueAsNumber IDL attributes;
select(),
stepDown(), and
stepUp() methods.
The value IDL attribute is
in mode value.
The input and change events apply.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
maxlength,
minlength,
multiple,
pattern,
placeholder,
size,
src, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
files,
selectionStart,
selectionEnd,
selectionDirection,
valueLow, and
valueHigh IDL attributes;
setRangeText(), and
setSelectionRange() methods.
The following fragment shows part of a calendar application. A user can specify a date and
time for a meeting (in his local time zone, probably, though the user agent can allow the user to
change that), and since the submitted data includes the time-zone offset, the application can
ensure that the meeting is shown at the correct time regardless of the time zones used by all the
participants.
<fieldset>
<legend>Add Meeting</legend>
<p><label>Meeting name: <input type=text name="meeting.label"></label>
<p><label>Meeting time: <input type=datetime name="meeting.start"></label>
</fieldset>
Date state (type=date)
When an input element's type attribute is in
the Date state, the rules in this section apply.
The input element represents a control for setting the element's
value to a string representing a specific date.
If the element is mutable, the user agent should allow the
user to change the date represented by its value, as obtained by parsing a
date from it. User agents must not allow the user to set the value to a non-empty string that is not a valid date
string. If the user agent provides a user interface for selecting a date, then the value must be set
to a valid date string representing the user's selection. User agents should allow
the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user
agent cannot convert to a valid date string, the control is suffering from bad
input.
See the introduction section for a discussion of
the difference between the input format and submission format for date, time, and number form
controls, and the implementation notes
regarding localization of form controls.
The value attribute, if specified and not empty, must
have a value that is a valid date string.
The value sanitization algorithm is as follows: If the value of the element is not a valid date string, then
set it to the empty string instead.
The min attribute, if specified, must have a value that is
a valid date string. The max attribute, if
specified, must have a value that is a valid date string.
The step attribute is expressed in days. The step scale factor is 86,400,000
(which converts the days to milliseconds, as used in the other algorithms). The default step is 1 day.
When the element is suffering from a step mismatch, the user agent may round the
element's value to the nearest date for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a date from input results in an
error, then return an error; otherwise, return the number of milliseconds elapsed from midnight
UTC on the morning of 1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z") to midnight UTC on the morning of the parsed date, ignoring leap seconds.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a
valid date string that represents the date that, in
UTC, is current input milliseconds after midnight UTC on the morning of
1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z").
The algorithm to convert a string to a
Date object, given a string input, is as follows:
If parsing a date from input results
in an error, then return an error; otherwise, return a new
Date object representing midnight UTC on the morning of the parsed date.
The algorithm to convert a
Date object to a string, given a Date object input, is as follows: Return a valid date string that
represents the date current at the time represented by input in the UTC time zone.
See the note on historical dates in the
Date and Time state section.
The following common input element content
attributes, IDL attributes, and methods apply to the element:
autocomplete,
list,
max,
min,
readonly,
required, and
step content attributes;
list,
value,
valueAsDate, and
valueAsNumber IDL attributes;
select(),
stepDown(), and
stepUp() methods.
The value IDL attribute is
in mode value.
The input and change events apply.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
maxlength,
minlength,
multiple,
pattern,
placeholder,
size,
src, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
selectionStart,
selectionEnd,
selectionDirection,
valueLow, and
valueHigh IDL attributes;
setRangeText(), and
setSelectionRange() methods.
Month state (type=month)
When an input element's type attribute is in
the Month state, the rules in this section apply.
The input element represents a control for setting the element's
value to a string representing a specific month.
If the element is mutable, the user agent should allow the
user to change the month represented by its value, as obtained by parsing a
month from it. User agents must not allow the user to set the value to a non-empty string that is not a valid month
string. If the user agent provides a user interface for selecting a month, then the value must be
set to a valid month string representing the user's selection. User agents should
allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user
agent cannot convert to a valid month string, the control is suffering from bad
input.
See the introduction section for a discussion of
the difference between the input format and submission format for date, time, and number form
controls, and the implementation notes
regarding localization of form controls.
The value attribute, if specified and not empty, must
have a value that is a valid month string.
The value sanitization algorithm is as follows: If the value of the element is not a valid month string,
then set it to the empty string instead.
The min attribute, if specified, must have a value that is
a valid month string. The max attribute, if
specified, must have a value that is a valid month string.
The step attribute is expressed in months. The step scale factor is 1 (there is no
conversion needed as the algorithms use months). The default step is 1 month.
When the element is suffering from a step mismatch, the user agent may round the
element's value to the nearest month for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a month from input results in an
error, then return an error; otherwise, return the number of months between January 1970 and the
parsed month.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a
valid month string that represents the month that
has input months between it and January 1970.
The algorithm to convert a string to a
Date object, given a string input, is as follows:
If parsing a month from input
results in an error, then return an error; otherwise, return a
new Date object representing midnight UTC on the morning of the first day of
the parsed month.
The algorithm to convert a
Date object to a string, given a Date object input, is as follows: Return a valid month string that
represents the month current at the time represented by input in the UTC time zone.
The following common input element content
attributes, IDL attributes, and methods apply to the element:
autocomplete,
list,
max,
min,
readonly,
required, and
step content attributes;
list,
value,
valueAsDate, and
valueAsNumber IDL attributes;
select(),
stepDown(), and
stepUp() methods.
The value IDL attribute is
in mode value.
The input and change events apply.
The following content attributes must not be specified and do not
apply to the element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
maxlength,
minlength,
multiple,
pattern,
placeholder,
size,
src, and
width.
The following IDL attributes and methods do not apply to the
element:
checked,
files,
selectionStart,
selectionEnd,
selectionDirection,
valueLow, and
valueHigh IDL attributes;
setRangeText(), and
setSelectionRange() methods.
Week state (type=week)
When an input element's type attribute is in
the Week state, the rules in this section apply.
The input element represents a control for setting the element's
value to a string representing a specific week.
If the element is mutable, the user agent should allow the
user to change the week represented by its value, as obtained by parsing a
week from it. User agents must not allow the user to set the value to a non-empty string that is not a valid week
string. If the user agent provides a user interface for selecting a week, then the value must be set
to a valid week string representing the user's selection. User agents should allow
the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user
agent cannot convert to a valid week string, the control is suffering from bad
input.
See the introduction section for a discussion of
the difference between the input format and submission format for date, time, and number form
controls, and the implementation notes
regarding localization of form controls.
The value attribute, if specified and not empty, must
have a value that is a valid week string.
The value sanitization algorithm is as follows: If the value of the element is not a valid week string, then
set it to the empty string instead.
The min attribute, if specified, must have a value that is
a valid week string. The max attribute, if
specified, must have a value that is a valid week string.
The step attribute is expressed in weeks. The step scale factor is 604,800,000
(which converts the weeks to milliseconds, as used in the other algorithms). The default step is 1 week. The default step base is −259,200,000 (the start
of week 1970-W01).
When the element is suffering from a step mismatch, the user agent may round the
element's value to the nearest week for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a week string from input results in
an error, then return an error; otherwise, return the number of milliseconds elapsed from midnight
UTC on the morning of 1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z") to midnight UTC on the morning of the Monday of the
parsed week, ignoring leap seconds.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a
valid week string that represents the week that, in
UTC, is current input milliseconds after midnight UTC on the morning of
1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z").
The algorithm to convert a string to a
Date object, given a string input, is as follows:
If parsing a week from input results
in an error, then return an error; otherwise, return a new
Date object representing midnight UTC on the morning of the Monday of the
parsed week.
The algorithm to convert a
Date object to a string, given a Date object input, is as follows: Return a valid week string that
represents the week current at the time represented by input in the UTC time zone.
The following common input element content attributes, IDL attributes, and
methods apply to the element:
autocomplete,
list,
max,
min,
readonly,
required, and
step content attributes;
list,
value,
valueAsDate, and
valueAsNumber IDL attributes;
select(),
stepDown(), and
stepUp() methods.
The value IDL attribute is in mode value.
The input and change events apply.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
maxlength,
minlength,
multiple,
pattern,
placeholder,
size,
src, and
width.
The following IDL attributes and methods do not apply to the element:
checked,
files,
selectionStart,
selectionEnd,
selectionDirection,
valueLow, and
valueHigh IDL attributes;
setRangeText(), and
setSelectionRange() methods.
Time state (type=time)
When an input element's type attribute is in
the Time state, the rules in this section apply.
The input element represents a control for setting the element's
value to a string representing a specific time.
If the element is mutable, the user agent should allow the
user to change the time represented by its value, as obtained by parsing a
time from it. User agents must not allow the user to set the value to a non-empty string that is not a valid time
string. If the user agent provides a user interface for selecting a time, then the value must be set
to a valid time string representing the user's selection. User agents should allow
the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user
agent cannot convert to a valid time string, the control is suffering from bad
input.
See the introduction section for a discussion of
the difference between the input format and submission format for date, time, and number form
controls, and the implementation notes
regarding localization of form controls.
The value attribute, if specified and not empty, must
have a value that is a valid time string.
The value sanitization algorithm is as follows: If the value of the element is not a valid time string, then
set it to the empty string instead.
The form control has a periodic domain.
The min attribute, if specified, must have a value that is
a valid time string. The max attribute, if
specified, must have a value that is a valid time string.
The step attribute is expressed in seconds. The step scale factor is 1000 (which
converts the seconds to milliseconds, as used in the other algorithms). The default step is 60 seconds.
When the element is suffering from a step mismatch, the user agent may round the
element's value to the nearest time for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a time from input results in an
error, then return an error; otherwise, return the number of milliseconds elapsed from midnight to
the parsed time on a day with no time changes.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a
valid time string that represents the time that is
input milliseconds after midnight on a day with no time changes.
The algorithm to convert a string to a
Date object, given a string input, is as follows:
If parsing a time from input results
in an error, then return an error; otherwise, return a new
Date object representing the parsed time in
UTC on 1970-01-01.
The algorithm to convert a
Date object to a string, given a Date object input, is as follows: Return a valid time string that
represents the UTC time component that is represented by input.
The following common input element content attributes, IDL attributes, and
methods apply to the element:
autocomplete,
list,
max,
min,
readonly,
required, and
step content attributes;
list,
value,
valueAsDate, and
valueAsNumber IDL attributes;
select(),
stepDown(), and
stepUp() methods.
The value IDL attribute is in mode value.
The input and change events apply.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
maxlength,
minlength,
multiple,
pattern,
placeholder,
size,
src, and
width.
The following IDL attributes and methods do not apply to the element:
checked,
files,
selectionStart,
selectionEnd,
selectionDirection,
valueLow, and
valueHigh IDL attributes;
setRangeText(), and
setSelectionRange() methods.
Number state (type=number)
When an input element's type attribute is in
the Number state, the rules in this section apply.
The input element represents a control for setting the element's
value to a string representing a number.
If the element is mutable, the user agent should allow the
user to change the number represented by its value, as
obtained from applying the rules for parsing floating-point number values to it. User
agents must not allow the user to set the value to a
non-empty string that is not a valid floating-point number. If the user agent
provides a user interface for selecting a number, then the value must be set to the best representation of the number representing the user's
selection as a floating-point number. User agents should allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the user
agent cannot convert to a valid floating-point number, the control is suffering
from bad input.
This specification does not define what user interface user agents are to use;
user agent vendors are encouraged to consider what would best serve their users' needs. For
example, a user agent in Persian or Arabic markets might support Persian and Arabic numeric input
(converting it to the format required for submission as described above). Similarly, a user agent
designed for Romans might display the value in Roman numerals rather than in decimal; or (more
realistically) a user agent designed for the French market might display the value with
apostrophes between thousands and commas before the decimals, and allow the user to enter a value
in that manner, internally converting it to the submission format described above.
The value attribute, if specified and not empty, must
have a value that is a valid floating-point number.
The value sanitization algorithm is as follows: If the value of the element is not a valid floating-point
number, then set it to the empty string instead.
The min attribute, if specified, must have a value that is
a valid floating-point number. The max attribute,
if specified, must have a value that is a valid floating-point number.
The step scale factor is
1. The default step is 1 (allowing only
integers to be selected by the user, unless the step
base has a non-integer value).
When the element is suffering from a step mismatch, the user agent may round the
element's value to the nearest number for which the element
would not suffer from a step mismatch. If
there are two such numbers, user agents are encouraged to pick the one nearest positive
infinity.
The algorithm to convert a string to a
number, given a string input, is as follows: If applying the
rules for parsing floating-point number values to input results
in an error, then return an error; otherwise, return the resulting number.
The algorithm to convert a number to a
string, given a number input, is as follows: Return a
valid floating-point number that represents input.
The following common input element content attributes, IDL attributes, and
methods apply to the element:
autocomplete,
list,
max,
min,
placeholder,
readonly,
required, and
step content attributes;
list,
value, and
valueAsNumber IDL attributes;
select(),
stepDown(), and
stepUp() methods.
The value IDL attribute is in mode value.
The input and change events apply.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
maxlength,
minlength,
multiple,
pattern,
size,
src, and
width.
The following IDL attributes and methods do not apply to the element:
checked,
files,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueLow, and
valueHigh IDL attributes;
setRangeText(), and
setSelectionRange() methods.
Here is an example of using a numeric input control:
<label>How much do you want to charge? $<input type=number min=0 step=0.01 name=price></label>
As described above, a user agent might support numeric input in the user's local format,
converting it to the format required for submission as described above. This might include
handling grouping separators (as in "872,000,000,000") and various decimal separators (such as
"3,99" vs "3.99") or using local digits (such as those in Arabic, Devanagari, Persian, and
Thai).
The type=number state is not appropriate for input that
happens to only consist of numbers but isn't strictly speaking a number. For example, it would be
inappropriate for credit card numbers or US postal codes. A simple way of determining whether to
use type=number is to consider whether it would make sense for the input
control to have a spinbox interface (e.g. with "up" and "down" arrows). Getting a credit card
number wrong by 1 in the last digit isn't a minor mistake, it's as wrong as getting every digit
incorrect. So it would not make sense for the user to select a credit card number using "up" and
"down" buttons. When a spinbox interface is not appropriate, type=text is
probably the right choice (possibly with a pattern
attribute).
Range state (type=range)
When an input element's type attribute is in
the Range state, the rules in this section apply.
How the Range state operates depends on whether the
multiple attribute is specified or not.
- When the
multiple attribute is not specified on the
element -
The input element represents a control for setting the element's
value to a string representing a number, but with the
caveat that the exact value is not important, letting UAs provide a simpler interface than they
do for the Number state.
If the element is mutable, the user agent should allow the
user to change the number represented by its value, as
obtained from applying the rules for parsing floating-point number values to it.
User agents must not allow the user to set the value to a
string that is not a valid floating-point number. If the user agent provides a user
interface for selecting a number, then the value must be
set to a best
representation of the number representing the user's selection as a floating-point
number. User agents must not allow the user to set the value to the empty string.
Constraint validation: While the user interface describes input that the
user agent cannot convert to a valid floating-point number, the control is
suffering from bad input.
The value attribute, if specified, must have a value
that is a valid floating-point number.
The value sanitization algorithm is as follows: If the value of the element is not a valid floating-point
number, then set it to the best representation, as a floating-point number, of the default value.
The default value is the minimum plus half the difference between the minimum and the maximum, unless the maximum is less than the minimum, in which case the default value is the minimum.
When the element is suffering from an underflow, the user agent must set the
element's value to the best representation, as a floating-point
number, of the minimum.
When the element is suffering from an overflow, if the maximum is not less than the minimum, the user agent must set the element's value to a valid floating-point number that
represents the maximum.
When the element is suffering from a step mismatch, the user agent must round
the element's value to the nearest number for which the
element would not suffer from a step
mismatch, and which is greater than or equal to the minimum, and, if the maximum is not less than the minimum, which is less than or equal to the maximum, if there is a number that matches these constraints.
If two numbers match these constraints, then user agents must use the one nearest to positive
infinity.
For example, the markup
<input type="range" min=0 max=100 step=20 value=50>
results in a range control whose initial value is 60.
Here is an example of a range control using an autocomplete list with the list attribute. This could be useful if there are values along
the full range of the control that are especially important, such as preconfigured light levels
or typical speed limits in a range control used as a speed control. The following markup
fragment:
<input type="range" min="-100" max="100" value="0" step="10" name="power" list="powers">
<datalist id="powers">
<option value="0">
<option value="-30">
<option value="30">
<option value="++50">
</datalist>
...with the following style sheet applied:
input { height: 75px; width: 49px; background: #D5CCBB; color: black; }
...might render as:
Note how the UA determined the orientation of the control from the ratio of the
style-sheet-specified height and width properties. The colours were similarly derived from the
style sheet. The tick marks, however, were derived from the markup. In particular, the step attribute has not affected the placement of tick marks,
the UA deciding to only use the author-specified completion values and then adding longer tick
marks at the extremes.
Note also how the invalid value ++50 was completely ignored.
For another example, consider the following markup fragment:
<input name=x type=range min=100 max=700 step=9.09090909 value=509.090909>
A user agent could display in a variety of ways, for instance:
Or, alternatively, for instance:
The user agent could pick which one to display based on the dimensions given in the style
sheet. This would allow it to maintain the same resolution for the tick marks, despite the
differences in width.
Finally, here is an example of a range control with two labeled values:
<input type="range" name="a" list="a-values">
<datalist id="a-values">
<option value="10" label="Low">
<option value="90" label="High">
</datalist>
With styles that make the control draw vertically, it might look as follows:
- When the
multiple attribute is specified on
the element -
The input element represents a control for setting the element's
values to two strings representing numbers, but
with the caveat that the exact values are not important, enabling UAs provide a graphical
interface rather than requiring the user to type the numbers directly.
If the element is mutable, the user agent should allow the
user to change either the first or second number represented by its values, as obtained from applying the rules for parsing
floating-point number values to them, and ensuring that the first value is never larger
than the second value. User agents must not allow the user to set either the first or second of
the values to a string that is not a valid
floating-point number. If the user agent provides a user interface for selecting a
number, then these values must be set to the best representations of
the numbers representing the user's selections as floating-point numbers. User agents
must not allow the user to set the values to the empty
string.
Constraint validation: While the user interface describes input that the
user agent cannot convert to a pair of valid
floating-point numbers, the control is suffering from bad input.
The value attribute, if specified, must have a value
that is a pair of valid floating-point numbers
separated by a single U+002C COMMA character (,).
The value sanitization algorithm is as follows:
Split on commas the element's value.
If there are not exactly two values, or if either value is not a valid
floating-point number, then let the element's values be a pair of values consisting of a best representation, as a
floating-point number, of the element's minimum
and the element's maximum, with the smaller value
first.
Othwerwise, let the element's values be the two
values, with the smaller value first.
Let the element's value be the result of
concatenating the element's values, separating them by
a single U+002C COMMA character (,), with the lower value coming first.
Whenever the user changes the element's values, the
user agent must set the element's value to the result of
concatenating the element's values, separating them by a
single U+002C COMMA character (,), with the lower value coming first.
When the element is suffering from an underflow, the user agent must set either
of the element's values that represent values less than
the minimum to the best representation, as a floating-point number,
of the minimum.
When the element is suffering from an overflow, if the maximum is not less than the minimum, the user agent must set either of the element's values that represent values greater than the maximum to a valid floating-point number that
represents the maximum.
When the element is suffering from a step mismatch, the user agent must round
the values represented by the element's values to, in
each case, the nearest number for which the element would not suffer from a step mismatch, and which is greater than or equal to the
minimum, and, if the maximum is not less than the minimum, which is less than or equal to the maximum, if there is a number that matches these constraints.
If two numbers match these constraints, then user agents must use the one nearest to positive
infinity.
Whenever the user agent changes the element's values
according to the three previous paragraphs, the user agent must set the element's value to the result of concatenating the element's values, separating them by a single U+002C COMMA character
(,), with the lower value coming first.
Consider a user interface that filters possible flights by departure and arrival time:
<form ...>
<fieldset>
<legend>Outbound flight time</legend>
<select ...>
<option>Departure
<option>Arrival
</select>
<p><output name=o1>00:00</output> – <output name=o2>24:00</output></p>
<input type=range multiple min=0 max=24 value=0,24 step=1.0 ...
oninput="o1.value = valueLow + ':00'; o2.value = valueHigh + ':00'">
</fieldset>
...
</form>
With appropriate styling, this might look like:
When the multiple attribute is set or removed, the
user agent must run the value sanitization algorithm.
In this state, the range and step constraints are enforced even during user input,
and there is no way to set the value to the empty string.
The min attribute, if specified, must have a value that is
a valid floating-point number. The default
minimum is 0. The max attribute, if specified, must
have a value that is a valid floating-point number. The default maximum is 100.
The step scale factor is
1. The default step is 1 (allowing only
integers, unless the min attribute has a non-integer
value).
The algorithm to convert a string to a
number, given a string input, is as follows: If applying the
rules for parsing floating-point number values to input results
in an error, then return an error; otherwise, return the resulting number.
The algorithm to convert a number to a
string, given a number input, is as follows: Return the best representation, as a
floating-point number, of input.
The following common input element content attributes, IDL attributes, and
methods apply to the element:
autocomplete,
list,
max,
min,
multiple, and
step content attributes;
list,
value, and
valueAsNumber IDL attributes;
stepDown() and
stepUp() methods.
The following common input IDL attribute applies to the element if the multiple content attribute is not specified:
valueAsNumber.
The following common input IDL attributes apply to the element if the multiple content attribute is specified:
valueLow and
valueHigh.
The value IDL attribute is in mode value.
The input and change events apply.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
maxlength,
minlength,
pattern,
placeholder,
readonly,
required,
size,
src, and
width.
The following IDL attributes and methods do not apply to the element:
checked,
files,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueLow, and
valueHigh IDL attributes;
select(),
setRangeText(), and
setSelectionRange() methods.
The following common input IDL attributes do not apply to the
element if the multiple content
attribute is not specified:
valueLow and
valueHigh.
The following common input IDL attribute does not
apply to the element if the multiple content attribute is specified:
valueAsNumber.
Colour state (type=color)
When an input element's type attribute is in
the Colour state, the rules in this section apply.
The input element represents a colour well control, for setting the
element's value to a string representing a simple
colour.
In this state, there is always a colour picked, and there is no way to set the
value to the empty string.
If the element is mutable, the user agent should allow the
user to change the colour represented by its value, as
obtained from applying the rules for parsing simple colour values to it. User agents
must not allow the user to set the value to a string that is
not a valid lowercase simple colour. If the user agent provides a user interface for
selecting a colour, then the value must be set to the result
of using the rules for serialising simple colour values to the user's selection. User
agents must not allow the user to set the value to the empty
string.
Constraint validation: While the user interface describes input that the user
agent cannot convert to a valid lowercase simple colour, the control is
suffering from bad input.
The value attribute, if specified and not empty, must
have a value that is a valid simple colour.
The value sanitization algorithm is as follows: If the value of the element is a valid simple colour, then
set it to the value of the element converted to ASCII
lowercase; otherwise, set it to the string "#000000".
The following common input element content attributes and IDL attributes apply to the element:
autocomplete and
list content attributes;
list and
value IDL attributes;
select() method.
The value IDL attribute is in mode value.
The input and change events apply.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
required,
size,
src,
step, and
width.
The following IDL attributes and methods do not apply to the element:
checked,
files,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
Checkbox state (type=checkbox)
When an input element's type attribute is in
the Checkbox state, the rules in this section
apply.
The input element represents a two-state control that represents the
element's checkedness state. If the element's checkedness state is true, the control represents a positive
selection, and if it is false, a negative selection. If the element's indeterminate IDL attribute is set to true, then the
control's selection should be obscured as if the control was in a third, indeterminate, state.
The control is never a true tri-state control, even if the element's indeterminate IDL attribute is set to true. The indeterminate IDL attribute only gives the appearance of a
third state.
If the element is mutable, then: The pre-click
activation steps consist of setting the element's checkedness to its opposite value (i.e. true if it is false,
false if it is true), and of setting the element's indeterminate IDL attribute to false. The canceled
activation steps consist of setting the checkedness and the element's indeterminate IDL attribute back to the values they had
before the pre-click activation steps were run. The activation behaviour
is to fire a simple event that bubbles named input at the element and then fire a simple event
that bubbles named change at the element.
If the element is not mutable, it has no activation
behaviour.
Constraint validation: If the element is required and its checkedness is false, then the element is suffering from
being missing.
- input .
indeterminate [ = value ] -
When set, overrides the rendering of checkbox
controls so that the current value is not visible.
The following common input element content attributes and IDL attributes apply to the element:
checked, and
required content attributes;
checked and
value IDL attributes.
The value IDL attribute is in mode default/on.
The input and change events apply.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
autocomplete,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
list,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
size,
src,
step, and
width.
The following IDL attributes and methods do not apply to the element:
files,
list,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
select(),
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
Radio Button state (type=radio)
When an input element's type attribute is in
the Radio Button state, the rules in this section
apply.
The input element represents a control that, when used in conjunction
with other input elements, forms a radio button group in which only one
control can have its checkedness state set to true. If
the element's checkedness state is true, the control
represents the selected control in the group, and if it is false, it indicates a control in the
group that is not selected.
The radio button group that contains an input element
a also contains all the other input elements b that fulfill all
of the following conditions:
A document must not contain an input element whose radio button group
contains only that element.
When any of the following phenomena occur, if the element's checkedness state is true after the occurrence, the checkedness state of all the other elements in the same radio
button group must be set to false:
If the element R is mutable, then: The
pre-click activation steps for R consist of getting a reference to the
element in R's radio button group that has its checkedness set to true, if any, and then setting
R's checkedness to true. The canceled
activation steps for R consist of checking if the element to which a reference
was obtained in the pre-click activation steps, if any, is still in what is now
R's radio button group, if it still has one, and if so, setting that
element's checkedness to true; or else, if there was no
such element, or that element is no longer in R's radio button group, or
if R no longer has a radio button group, setting R's checkedness to false. The activation behaviour for
R is to fire a simple event that bubbles named input at R and then fire a simple event
that bubbles named change at R.
If the element is not mutable, it has no activation
behaviour.
Constraint validation: If an element in the radio button group is required, and all of the input elements in the
radio button group have a checkedness that is
false, then the element is suffering from being missing.
If none of the radio buttons in a radio button group are checked when
they are inserted into the document, then they will all be initially unchecked in the interface,
until such time as one of them is checked (either by the user or by script).
The following common input element content attributes and IDL attributes apply to the element:
checked and
required content attributes;
checked and
value IDL attributes.
The value IDL attribute is in mode default/on.
The input and change events apply.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
autocomplete,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
list,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
size,
src,
step, and
width.
The following IDL attributes and methods do not apply to the element:
files,
list,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
select(),
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
File Upload state (type=file)
When an input element's type attribute is in
the File Upload state, the rules in this section
apply.
The input element represents a list of selected files, each file consisting of a file
name, a file type, and a file body (the contents of the file).
File names must not contain path components, even
in the case that a user has selected an entire directory hierarchy or multiple files with the same
name from different directories. Path components, for
the purposes of the File Upload state, are those parts
of file names that are separated by U+005C REVERSE SOLIDUS character (\) characters.
Unless the multiple attribute is set, there must be
no more than one file in the list of selected
files.
If the element is mutable, then the element's
activation behaviour is to run the following steps:
If the algorithm is not , then abort these steps
without doing anything else.
Return, but continue running these steps in parallel.
Optionally, wait until any prior execution of this algorithm has terminated.
Display a prompt to the user requesting that the user specify some files. If the multiple attribute is not set, there must be no more than one
file selected; otherwise, any number may be selected. Files can be from the filesystem or created
on the fly, e.g. a picture taken from a camera connected to the user's device.
Wait for the user to have made their selection.
Queue a task to first update the element's selected files so that it represents the user's
selection, then fire a simple event that bubbles named input at the input element, and finally fire
a simple event that bubbles named change at the
input element.
If the element is mutable, the user agent should allow the
user to change the files on the list in other ways also, e.g. adding or removing files by
drag-and-drop. When the user does so, the user agent must queue a task to first
update the element's selected files so that
it represents the user's new selection, then fire a simple event that bubbles named
input at the input element, and finally
fire a simple event that bubbles named change at the input element.
If the element is not mutable, it has no activation
behaviour and the user agent must not allow the user to change the element's selection.
Constraint validation: If the element is required and the list of selected files is empty, then the element is
suffering from being missing.
The accept attribute may be specified to
provide user agents with a hint of what file types will be accepted.
If specified, the attribute must consist of a set of comma-separated tokens, each
of which must be an ASCII case-insensitive match for one of the following:
- The string "
audio/*" - Indicates that sound files are accepted.
- The string "
video/*" - Indicates that video files are accepted.
- The string "
image/*" - Indicates that image files are accepted.
- A valid MIME type with no parameters
- Indicates that files of the specified type are accepted.
- A string whose first character is a U+002E FULL STOP character (.)
- Indicates that files with the specified file extension are accepted.
The tokens must not be ASCII case-insensitive matches for any of the other tokens
(i.e. duplicates are not allowed). To obtain the list of tokens from the
attribute, the user agent must split the attribute value on
commas.
User agents may use the value of this attribute to display a more appropriate user interface
than a generic file picker. For instance, given the value image/*, a user
agent could offer the user the option of using a local camera or selecting a photograph from their
photo collection; given the value audio/*, a user agent could offer the user
the option of recording a clip using a headset microphone.
User agents should prevent the user from selecting files that are not accepted by one (or more)
of these tokens.
Authors are encouraged to specify both any MIME types and any corresponding
extensions when looking for data in a specific format.
For example, consider an application that converts Microsoft Word documents to Open Document
Format files. Since Microsoft Word documents are described with a wide variety of MIME types and
extensions, the site can list several, as follows:
<input type="file" accept=".doc,.docx,.xml,application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document">
On platforms that only use file extensions to describe file types, the extensions listed here
can be used to filter the allowed documents, while the MIME types can be used with the system's
type registration table (mapping MIME types to extensions used by the system), if any, to
determine any other extensions to allow. Similarly, on a system that does not have file names or
extensions but labels documents with MIME types internally, the MIME types can be used to pick
the allowed files, while the extensions can be used if the system has an extension registration
table that maps known extensions to MIME types used by the system.
Extensions tend to be ambiguous (e.g. there are an untold number of formats
that use the ".dat" extension, and users can typically quite easily rename
their files to have a ".doc" extension even if they are not Microsoft Word
documents), and MIME types tend to be unreliable (e.g. many formats have no formally registered
types, and many formats are in practice labeled using a number of different MIME types). Authors
are reminded that, as usual, data received from a client should be treated with caution, as it may
not be in an expected format even if the user is not hostile and the user agent fully obeyed the
accept attribute's requirements.
For historical reasons, the value IDL attribute prefixes
the file name with the string "C:\fakepath\". Some legacy user agents
actually included the full path (which was a security vulnerability). As a result of this,
obtaining the file name from the value IDL attribute in a
backwards-compatible way is non-trivial. The following function extracts the file name in a
suitably compatible manner:
function extractFilename(path) {
if (path.substr(0, 12) == "C:\\fakepath\\")
return path.substr(12); // modern browser
var x;
x = path.lastIndexOf('/');
if (x >= 0) // Unix-based path
return path.substr(x+1);
x = path.lastIndexOf('\\');
if (x >= 0) // Windows-based path
return path.substr(x+1);
return path; // just the file name
}
This can be used as follows:
<p><input type=file name=image onchange="updateFilename(this.value)"></p>
<p>The name of the file you picked is: <span id="filename">(none)</span></p>
<script>
function updateFilename(path) {
var name = extractFilename(path);
document.getElementById('filename').textContent = name;
}
</script>
The following common input element content attributes and IDL attributes apply to the element:
accept,
multiple, and
required content attributes;
files and
value IDL attributes;
select() method.
The value IDL attribute is in mode filename.
The input and change events apply.
The following content attributes must not be specified and do not apply to the
element:
alt,
autocomplete,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
list,
max,
maxlength,
min,
minlength,
pattern,
placeholder,
readonly,
size,
src,
step, and
width.
The element's value attribute must be omitted.
The following IDL attributes and methods do not apply to the element:
checked,
list,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
Submit Button state (type=submit)
When an input element's type attribute is in
the Submit Button state, the rules in this section
apply.
The input element represents a button that, when activated, submits
the form. If the element has a value
attribute, the button's label must be the value of that attribute; otherwise, it must be an
implementation-defined string that means "Submit" or some such. The element is a button, specifically a submit
button.
Since the default label is implementation-defined, and the width of the button
typically depends on the button's label, the button's width can leak a few bits of fingerprintable
information. These bits are likely to be strongly correlated to the identity of the user agent and
the user's locale.
If the element is mutable, then the element's
activation behaviour is as follows: if the element has a form owner,
and the element's node document is fully active,
submit the form owner from the
input element; otherwise, do nothing.
If the element is not mutable, it has no activation
behaviour.
The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes for form
submission.
The formnovalidate attribute can be
used to make submit buttons that do not trigger the constraint validation.
The following common input element content attributes and IDL attributes apply to the element:
formaction,
formenctype,
formmethod,
formnovalidate, and
formtarget content attributes;
value IDL attribute.
The value IDL attribute is in mode default.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
autocomplete,
checked,
dirname,
height,
inputmode,
list,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
required,
size,
src,
step, and
width.
The following IDL attributes and methods do not apply to the element:
checked,
files,
list,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
select(),
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
The input and change events do not apply.
Image Button state (type=image)
When an input element's type attribute is in
the Image Button state, the rules in this section
apply.
The input element represents either an image from which a user can
select a coordinate and submit the form, or alternatively a button from which the user can submit
the form. The element is a button, specifically a submit button.
The coordinate is sent to the server during form submission by sending two entries for the element, derived from the name
of the control but with ".x" and ".y" appended to the
name with the x and y components of the coordinate
respectively.
The image is given by the src attribute. The
src attribute must be present, and must contain a valid
non-empty URL potentially surrounded by spaces referencing a non-interactive, optionally
animated, image resource that is neither paged nor scripted.
When any of the following events occur, unless the user agent cannot support images, or its
support for images has been disabled, or the user agent only fetches elements on demand, or the
src attribute's value is the empty string, the user agent must
resolve the value of the src attribute, relative to the element, and if that is successful,
must fetch the resulting absolute URL:
- The
input element's type attribute is first
set to the Image Button state (possibly when the
element is first created), and the src attribute is
present. - The
input element's type attribute is
changed back to the Image Button state, and the src attribute is present, and its value has changed since the last
time the type attribute was in the Image Button state. - The
input element's type attribute is in
the Image Button state, and the src attribute is set or changed.
Fetching the image must delay the load event of the element's node document until the
task that is queued by the
networking task source once the resource has been fetched
(defined below) has been run.
If the image was successfully obtained, with no network errors, and the image's type is a
supported image type, and the image is a valid image of that type, then the image is said to be
available. If this is true before the image is
completely downloaded, each task that is queued by the networking task source while the image is being fetched must update the presentation of the image appropriately.
The user agent should apply the image sniffing
rules to determine the type of the image, with the image's associated Content-Type headers giving the official
type. If these rules are not applied, then the type of the image must be the type given by
the image's associated Content-Type headers.
User agents must not support non-image resources with the input element. User
agents must not run executable code embedded in the image resource. User agents must only display
the first page of a multipage resource. User agents must not allow the resource to act in an
interactive fashion, but should honor any animation in the resource.
The task that is queued by
the networking task source once the resource has been fetched, must, if the download was successful and the image is available, queue a task to fire a simple
event named load at the input element; and
otherwise, if the fetching process fails without a response from the remote server, or completes
but the image is not a valid or supported image, queue a task to fire a simple
event named error on the input element.
The alt attribute provides the textual label for
the button for users and user agents who cannot use the image. The alt attribute must be present, and must contain a non-empty string
giving the label that would be appropriate for an equivalent button if the image was
unavailable.
The input element supports dimension attributes.
If the src attribute is set, and the image is available and the user agent is configured to display that image,
then: The element represents a control for selecting a coordinate from the image specified by the
src attribute; if the element is mutable, the user agent should allow the user to select this coordinate, and the element's activation
behaviour is as follows: if the element has a form owner, and the element's
node document is fully active, take the user's selected coordinate, and submit the input element's form owner
from the input element. If the user activates the control without explicitly
selecting a coordinate, then the coordinate (0,0) must be assumed.
Otherwise, the element represents a submit button whose label is given by the
value of the alt attribute; if the element is mutable, then the element's activation behaviour is as
follows: if the element has a form owner, and the element's node document is
fully active, set the selected
coordinate to (0,0), and submit the
input element's form owner from the input element.
In either case, if the element is mutable but has no
form owner or the element's node document is not fully active,
then its activation behaviour must be to do nothing. If the element is not mutable, it has no activation behaviour.
The selected coordinate must consist of
an x-component and a y-component. The coordinates
represent the position relative to the edge of the image, with the coordinate space having the
positive x direction to the right, and the positive y
direction downwards.
The x-component must be a valid integer representing a number
x in the range −(borderleft+paddingleft) ≤ x ≤ width+borderright+paddingright, where width is the rendered width of the image, borderleft is the width of the border on the left of the image, paddingleft is the width of the padding on the left of the
image, borderright is the width of the border on the right
of the image, and paddingright is the width of the padding
on the right of the image, with all dimensions given in CSS pixels.
The y-component must be a valid integer representing a number
y in the range −(bordertop+paddingtop) ≤ y ≤ height+borderbottom+paddingbottom, where
height is the rendered height of the image, bordertop is the width of the border above the image, paddingtop is the width of the padding above the image, borderbottom is the width of the border below the image, and paddingbottom is the width of the padding below the image, with
all dimensions given in CSS pixels.
Where a border or padding is missing, its width is zero CSS pixels.
The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes for form
submission.
- image .
width [ = value ] - image .
height [ = value ] -
These attributes return the actual rendered dimensions of the image, or zero if the
dimensions are not known.
They can be set, to change the corresponding content attributes.
The following common input element content attributes and IDL attributes apply to the element:
alt,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
src, and
width content attributes;
value IDL attribute.
The value IDL attribute is in mode default.
The following content attributes must not be specified and do not apply to the
element:
accept,
autocomplete,
checked,
dirname,
inputmode,
list,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
required,
size, and
step.
The element's value attribute must be omitted.
The following IDL attributes and methods do not apply to the element:
checked,
files,
list,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
select(),
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
The input and change events do not apply.
Many aspects of this state's behaviour are similar to the behaviour of the
img element. Readers are encouraged to read that section, where many of the same
requirements are described in more detail.
Take the following form:
<form action="process.cgi">
<input type=image src=map.png name=where alt="Show location list">
</form>
If the user clicked on the image at coordinate (127,40) then the URL used to submit the form
would be "process.cgi?where.x=127&where.y=40".
(In this example, it's assumed that for users who don't see the map, and who instead just see
a button labeled "Show location list", clicking the button will cause the server to show a list
of locations to pick from instead of the map.)
Reset Button state (type=reset)
When an input element's type attribute is in
the Reset Button state, the rules in this section
apply.
The input element represents a button that, when activated, resets
the form. If the element has a value
attribute, the button's label must be the value of that attribute; otherwise, it must be an
implementation-defined string that means "Reset" or some such. The element is a button.
Since the default label is implementation-defined, and the width of the button
typically depends on the button's label, the button's width can leak a few bits of fingerprintable
information. These bits are likely to be strongly correlated to the identity of the user agent and
the user's locale.
If the element is mutable, then the element's
activation behaviour, if the element has a form owner and the element's
node document is fully active, is to reset the form owner; otherwise, it is to do
nothing.
If the element is not mutable, it has no activation
behaviour.
Constraint validation: The element is barred from constraint
validation.
The value IDL attribute applies to this element and is in mode default.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
autocomplete,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
list,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
required,
size,
src,
step, and
width.
The following IDL attributes and methods do not apply to the element:
checked,
files,
list,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
select(),
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
The input and change events do not apply.
Button state (type=button)
When an input element's type attribute is in
the Button state, the rules in this section apply.
The input element represents a button with no default behaviour. A
label for the button must be provided in the value
attribute, though it may be the empty string. If the element has a value attribute, the button's label must be the value of that
attribute; otherwise, it must be the empty string. The element is a button.
If the element is mutable, the element's activation
behaviour is to do nothing.
If the element is not mutable, it has no activation
behaviour.
Constraint validation: The element is barred from constraint
validation.
The value IDL attribute applies to this element and is in mode default.
The following content attributes must not be specified and do not apply to the
element:
accept,
alt,
autocomplete,
checked,
dirname,
formaction,
formenctype,
formmethod,
formnovalidate,
formtarget,
height,
inputmode,
list,
max,
maxlength,
min,
minlength,
multiple,
pattern,
placeholder,
readonly,
required,
size,
src,
step, and
width.
The following IDL attributes and methods do not apply to the element:
checked,
files,
list,
selectionStart,
selectionEnd,
selectionDirection,
valueAsDate,
valueAsNumber,
valueLow, and
valueHigh IDL attributes;
select(),
setRangeText(),
setSelectionRange(),
stepDown(), and
stepUp() methods.
The input and change events do not apply.
Implemention notes regarding localization of form controls
This section is non-normative.
The formats shown to the user in date, time, and number controls is independent of the format
used for form submission.
Browsers are encouraged to use user interfaces that present dates, times, and numbers according
to the conventions of either the locale implied by the input element's
language or the user's preferred locale. Using the page's locale will ensure
consistency with page-provided data.
For example, it would be confusing to users if an American English page claimed
that a Cirque De Soleil show was going to be showing on 02/03, but their
browser, configured to use the British English locale, only showed the date 03/02 in the ticket purchase date picker. Using the page's locale would at least ensure that the
date was presented in the same format everywhere. (There's still a risk that the user would end up
arriving a month late, of course, but there's only so much that can be done about such cultural
differences...)
Common input element attributes
These attributes only apply to an input
element if its type attribute is in a state whose definition
declares that the attribute applies. When an attribute
doesn't apply to an input element, user agents must
ignore the attribute, regardless of the requirements and definitions below.
The readonly attribute is a boolean
attribute that controls whether or not the user can edit the form control. When specified, the element is not mutable.
Constraint validation: If the readonly attribute is specified on an input
element, the element is barred from constraint validation.
The difference between disabled and readonly is that read-only controls are still focusable, so the
user can still select the text and interact with it, whereas disabled controls are entirely
non-interactive. (For this reason, only text controls can be made read-only: it wouldn't make
sense for checkboxes or buttons, for instances.)
In the following example, the existing product identifiers cannot be modified, but they are
still displayed as part of the form, for consistency with the row representing a new product
(where the identifier is not yet filled in).
<form action="products.cgi" method="post" enctype="multipart/form-data">
<table>
<tr> <th> Product ID <th> Product name <th> Price <th> Action
<tr>
<td> <input readonly="readonly" name="1.pid" value="H412">
<td> <input required="required" name="1.pname" value="Floor lamp Ulke">
<td> $<input required="required" type="number" min="0" step="0.01" name="1.pprice" value="49.99">
<td> <button formnovalidate="formnovalidate" name="action" value="delete:1">Delete</button>
<tr>
<td> <input readonly="readonly" name="2.pid" value="FG28">
<td> <input required="required" name="2.pname" value="Table lamp Ulke">
<td> $<input required="required" type="number" min="0" step="0.01" name="2.pprice" value="24.99">
<td> <button formnovalidate="formnovalidate" name="action" value="delete:2">Delete</button>
<tr>
<td> <input required="required" name="3.pid" value="" pattern="[A-Z0-9]+">
<td> <input required="required" name="3.pname" value="">
<td> $<input required="required" type="number" min="0" step="0.01" name="3.pprice" value="">
<td> <button formnovalidate="formnovalidate" name="action" value="delete:3">Delete</button>
</table>
<p> <button formnovalidate="formnovalidate" name="action" value="add">Add</button> </p>
<p> <button name="action" value="update">Save</button> </p>
</form>
The required attribute is a boolean
attribute. When specified, the element is required.
Constraint validation: If the element is required, and its value
IDL attribute applies and is in the mode value, and the element is mutable, and the element's value is the empty string, then the element is suffering
from being missing.
The following form has two required fields, one for an e-mail address and one for a password.
It also has a third field that is only considered valid if the user types the same password in
the password field and this third field.
<h1>Create new account</h1>
<form action="/newaccount" method=post
oninput="up2.setCustomValidity(up2.value != up.value ? 'Passwords do not match.' : '')">
<p>
<label for="username">E-mail address:</label>
<input id="username" type=email required name=un>
<p>
<label for="password1">Password:</label>
<input id="password1" type=password required name=up>
<p>
<label for="password2">Confirm password:</label>
<input id="password2" type=password name=up2>
<p>
<input type=submit value="Create account">
</form>
For radio buttons, the required attribute is
satisfied if any of the radio buttons in the group is
selected. Thus, in the following example, any of the radio buttons can be checked, not just the
one marked as required:
<fieldset>
<legend>Did the movie pass the Bechdel test?</legend>
<p><label><input type="radio" name="bechdel" value="no-characters"> No, there are not even two female characters in the movie. </label>
<p><label><input type="radio" name="bechdel" value="no-names"> No, the female characters never talk to each other. </label>
<p><label><input type="radio" name="bechdel" value="no-topic"> No, when female characters talk to each other it's always about a male character. </label>
<p><label><input type="radio" name="bechdel" value="yes" required> Yes. </label>
<p><label><input type="radio" name="bechdel" value="unknown"> I don't know. </label>
</fieldset>
To avoid confusion as to whether a radio button group is required or not, authors
are encouraged to specify the attribute on all the radio buttons in a group. Indeed, in general,
authors are encouraged to avoid having radio button groups that do not have any initially checked
controls in the first place, as this is a state that the user cannot return to, and is therefore
generally considered a poor user interface.
The multiple attribute is a boolean
attribute that indicates whether the user is to be allowed to specify more than one
value.
The following extract shows how an e-mail client's "Cc" field could accept multiple e-mail
addresses.
<label>Cc: <input type=email multiple name=cc></label>
If the user had, amongst many friends in his user contacts database, two friends "Arthur Dent"
(with address "art@example.net") and "Adam Josh" (with address "adamjosh@example.net"), then,
after the user has typed "a", the user agent might suggest these two e-mail addresses to the
user.
The page could also link in the user's contacts database from the site:
<label>Cc: <input type=email multiple name=cc list=contacts></label>
...
<datalist id="contacts">
<option value="hedral@damowmow.com">
<option value="pillar@example.com">
<option value="astrophy@cute.example">
<option value="astronomy@science.example.org">
</datalist>
Suppose the user had entered "bob@example.net" into this text field, and then started typing a
second e-mail address starting with "a". The user agent might show both the two friends mentioned
earlier, as well as the "astrophy" and "astronomy" values given in the datalist
element.
The following extract shows how an e-mail client's "Attachments" field could accept multiple
files for upload.
<label>Attachments: <input type=file multiple name=att></label>
The pattern attribute specifies a regular
expression against which the control's value, or, when the
multiple attribute applies and is set, the control's values, are to be checked.
If specified, the attribute's value must match the JavaScript Pattern
production. [[!ECMA262]]
If an input element has a pattern
attribute specified, and the attribute's value, when compiled as a JavaScript regular expression
with only the "u" flag specified, compiles successfully, then the resulting regular expression is the element's
compiled pattern regular expression. If the element has no such attribute, or if the
value doesn't compile successfully, then the element has no compiled pattern regular
expression. [[!ECMA262]]
Constraint validation: If the element's value is not the empty string, and either the element's multiple attribute is not specified or it does not apply to the input element given its type attribute's current state, and the element has a
compiled pattern regular expression but that regular expression does not match the
entirety of the element's value, then the element is
suffering from a pattern mismatch.
Constraint validation: If the element's value is not the empty string, and the element's multiple attribute is specified and applies to the input element, and the element has
a compiled pattern regular expression but that regular expression does not match the
entirety of each of the element's values, then the
element is suffering from a pattern mismatch.
The compiled pattern regular expression, when matched against a string, must have
its start anchored to the start of the string and its end anchored to the end of the string.
This implies that the regular expression language used for this attribute is the
same as that used in JavaScript, except that the pattern
attribute is matched against the entire value, not just any subset (somewhat as if it implied a
^(?: at the start of the pattern and a )$ at the
end).
When an input element has a pattern
attribute specified, authors should include a title attribute to give a description of the pattern.
User agents may use the contents of this attribute, if it is present, when informing the user that
the pattern is not matched, or at any other suitable time, such as in a tooltip or read out by
assistive technology when the control gains focus.
Relying on the title attribute for the visual display
of text content is currently discouraged as many user agents do not expose the attribute in an accessible manner
as required by this specification (e.g. requiring a pointing device such as a mouse to cause a tooltip to appear,
which excludes keyboard-only users and touch-only users, such as anyone with a modern phone or
tablet).
For example, the following snippet:
<label> Part number:
<input pattern="[0-9][A-Z]{3}" name="part"
title="A part number is a digit followed by three uppercase letters."/>
</label>
...could cause the UA to display an alert such as:
A part number is a digit followed by three uppercase letters.
You cannot submit this form when the field is incorrect.
When a control has a pattern attribute, the title attribute, if used, must describe the pattern. Additional
information could also be included, so long as it assists the user in filling in the control.
Otherwise, assistive technology would be impaired.
For instance, if the title attribute contained the caption of the control,
assistive technology could end up saying something like The text you have entered does not
match the required pattern. Birthday, which is not useful.
UAs may still show the title in non-error situations (for
example, as a tooltip when hovering over the control), so authors should be careful not to word
titles as if an error has necessarily occurred.
The min and max attributes
Some form controls can have explicit constraints applied limiting the allowed range of values
that the user can provide. Normally, such a range would be linear and continuous. A form control
can have a periodic domain, however, in which case the
form control's broadest possible range is finite, and authors can specify explicit ranges within
it that span the boundaries.
Specifically, the broadest range of a type=time control is midnight to midnight (24 hours), and
authors can set both continuous linear ranges (such as 9pm to 11pm) and discontinuous ranges
spanning midnight (such as 11pm to 1am).
The min and max attributes indicate the allowed range of values for
the element.
Their syntax is defined by the section that defines the type attribute's current state.
If the element has a min attribute, and the result of
applying the algorithm to convert a string to a
number to the value of the min attribute is a number,
then that number is the element's minimum; otherwise, if the
type attribute's current state defines a default minimum, then that is the minimum; otherwise, the element has no minimum.
The min attribute also defines the step base.
If the element has a max attribute, and the result of
applying the algorithm to convert a string to a
number to the value of the max attribute is a number,
then that number is the element's maximum; otherwise, if the
type attribute's current state defines a default maximum, then that is the maximum; otherwise, the element has no maximum.
If the element does not have a periodic domain, the
max attribute's value (the maximum) must not be less than the min attribute's value (its minimum).
If an element that does not have a periodic
domain has a maximum that is less than its minimum, then so long as the element has a value, it will either be suffering from an underflow
or suffering from an overflow.
An element has a reversed range if it has a periodic domain and its
maximum is less than its minimum.
An element has range limitations if it has a defined
minimum or a defined maximum.
How these range limitations apply depends on whether the element has a multiple attribute.
- If the element does not have a
multiple attribute
specified or if the multiple attribute does not apply -
Constraint validation: When the element has a minimum and does not have a
reversed range, and the result of applying the algorithm to convert a string to a number to
the string given by the element's value is a number, and
the number obtained from that algorithm is less than the minimum, the element is suffering from an
underflow.
Constraint validation: When the element has a maximum and does not have a
reversed range, and the result of applying the algorithm to convert a string to a number to
the string given by the element's value is a number, and
the number obtained from that algorithm is more than the maximum, the element is suffering from an
overflow.
Constraint validation: When an element has a reversed range,
and the result of applying the algorithm to
convert a string to a number to the string given by the element's value is a number, and the number obtained from that algorithm
is more than the maximum and less than the minimum, the element is simultaneously suffering from an
underflow and suffering from an overflow.
- If the element does have a
multiple attribute
specified and the multiple attribute does apply -
Constraint validation: When the element has a minimum, and the result of applying the algorithm to convert a string to a number to
any of the strings in the element's values is a number
that is less than the minimum, the element is
suffering from an underflow.
Constraint validation: When the element has a maximum, and the result of applying the algorithm to convert a string to a number to
any of the strings in the element's values is a number
that is more than the maximum, the element is
suffering from an overflow.
The following date control limits input to dates that are before the 1980s:
<input name=bday type=date max="1979-12-31">
The following number control limits input to whole numbers greater than zero:
<input name=quantity required="" type="number" min="1" value="1">
The following time control limits input to those minutes that occur between 9pm and 6am,
defaulting to midnight:
<input name="sleepStart" type=time min="21:00" max="06:00" step="60" value="00:00">
The step attribute
The step attribute indicates the granularity
that is expected (and required) of the value or values, by limiting the allowed values. The
section that defines the type attribute's current state also
defines the default step, the step scale factor, and in some cases the default step base, which are used in processing the
attribute as described below.
The step attribute, if specified, must either have a
value that is a valid floating-point number that parses to a number that is greater than zero, or must have a
value that is an ASCII case-insensitive match for the string "any".
The attribute provides the allowed value step for the
element, as follows:
- If the attribute is absent, then the allowed value
step is the default step multiplied by the
step scale factor.
- Otherwise, if the attribute's value is an ASCII case-insensitive match for the
string "
any", then there is no allowed
value step. - Otherwise, if the rules for parsing floating-point number values, when they are
applied to the attribute's value, return an error, zero, or a number less than zero, then the
allowed value step is the default step multiplied by the step scale factor.
- Otherwise, the allowed value step is the number
returned by the rules for parsing floating-point number values when they are applied
to the attribute's value, multiplied by the step scale
factor.
The step base is the value returned by the following
algorithm:
If the element has a min content attribute, and the
result of applying the algorithm to convert a
string to a number to the value of the min content
attribute is not an error, then return that result and abort these steps.
-
If the element does not have a multiple attribute
specified or if the multiple attribute does not apply, then: if the element has a value content attribute, and the result of applying the algorithm to convert a string to a number to
the value of the value content attribute is not an error,
then return that result and abort these steps.
Otherwise, the element's type attribute is in the Range state and the element has a multiple attribute specified: run these substeps:
If the element does not have a value content
attribute, skip these substeps.
Split on commas the value of the value content attribute.
If the result of the previous step was not exactly two values, or if either gets an
error when you apply the algorithm to convert
a string to a number, then skip these substeps.
Return the lower of the two numbers obtained in the previous step, and abort these
steps.
If a default step base is defined for
this element given its type attribute's state, then return
it and abort these steps.
Return zero.
How these range limitations apply depends on whether the element has a multiple attribute.
- If the element does not have a
multiple attribute
specified or if the multiple attribute does not apply -
Constraint validation: When the element has an allowed value step, and the result of applying the algorithm to convert a string to a number to
the string given by the element's value is a number, and
that number subtracted from the step base is not an
integral multiple of the allowed value step, the
element is suffering from a step mismatch.
- If the element does have a
multiple attribute
specified and the multiple attribute does apply -
Constraint validation: When the element has an allowed value step, and the result of applying the algorithm to convert a string to a number to
any of the strings in the element's values is a number
that, when subtracted from the step base, is not an
integral multiple of the allowed value step, the
element is suffering from a step mismatch.
The following range control only accepts values in the range 0..1, and allows 256 steps in
that range:
<input name=opacity type=range min=0 max=1 step=0.00392156863>
The following control allows any time in the day to be selected, with any accuracy (e.g.
thousandth-of-a-second accuracy or more):
<input name=favtime type=time step=any>
Normally, time controls are limited to an accuracy of one minute.
The list attribute
The list attribute is used to identify an
element that lists predefined options suggested to the user.
If present, its value must be the ID of a datalist
element in the same document.
The suggestions source element is the first element in
the document in tree order to have an ID equal to the
value of the list attribute, if that element is a
datalist element. If there is no list attribute,
or if there is no element with that ID, or if the first element
with that ID is not a datalist element, then there is
no suggestions source element.
If there is a suggestions source element, then, when
the user agent is allowing the user to edit the input element's value, the user agent should offer the suggestions represented by
the suggestions source element to the user in a manner
suitable for the type of control used. The user agent may use the suggestion's label to identify the suggestion if appropriate.
User agents are encouraged to filter the suggestions represented by the suggestions source element when the number of suggestions is
large, including only the most relevant ones (e.g. based on the user's input so far). No precise
threshold is defined, but capping the list at four to seven values is reasonable.
How user selections of suggestions are handled depends on whether the element is a control
accepting a single value only, or whether it accepts multiple values:
- If the element does not have a
multiple attribute
specified or if the multiple attribute does not apply -
When the user selects a suggestion, the input element's value must be set to the selected suggestion's value, as if the user had written that value himself.
- If the element's
type attribute is in the Range state and the element has a multiple attribute specified -
When the user selects a suggestion, the user agent must identify which value in the element's
values the user intended to update, and must then update
the element's values so that the relevant value is
changed to the value given by the selected suggestion's value, as if the user had himself set it to that value.
- If the element's
type attribute is in the Email state and the element has a multiple attribute specified -
When the user selects a suggestion, the user agent must either add a new entry to the
input element's values, whose value
is the selected suggestion's value, or change an
existing entry in the input element's values to have the value given by the selected
suggestion's value, as if the user had himself added
an entry with that value, or edited an existing entry to be that value. Which behaviour is to be
applied depends on the user interface in a user-agent-defined manner.
If the list attribute does not
apply, there is no suggestions source element.
This URL field offers some suggestions.
<label>Homepage: <input name=hp type=url list=hpurls></label>
<datalist id=hpurls>
<option value="http://www.google.com/" label="Google">
<option value="http://www.reddit.com/" label="Reddit">
</datalist>
Other URLs from the user's history might show also; this is up to the user agent.
This example demonstrates how to design a form that uses the autocompletion list feature while
still degrading usefully in legacy user agents.
If the autocompletion list is merely an aid, and is not important to the content, then simply
using a datalist element with children option elements is enough. To
prevent the values from being rendered in legacy user agents, they need to be placed inside the
value attribute instead of inline.
<p>
<label>
Enter a breed:
<input type="text" name="breed" list="breeds">
<datalist id="breeds">
<option value="Abyssinian">
<option value="Alpaca">
<!-- ... -->
</datalist>
</label>
</p>
However, if the values need to be shown in legacy UAs, then fallback content can be placed
inside the datalist element, as follows:
<p>
<label>
Enter a breed:
<input type="text" name="breed" list="breeds">
</label>
<datalist id="breeds">
<label>
or select one from the list:
<select name="breed">
<option value=""> (none selected)
<option>Abyssinian
<option>Alpaca
<!-- ... -->
</select>
</label>
</datalist>
</p>
The fallback content will only be shown in UAs that don't support datalist. The
options, on the other hand, will be detected by all UAs, even though they are not children of the
datalist element.
Note that if an option element used in a datalist is selected, it will be selected by default by legacy UAs
(because it affects the select), but it will not have any effect on the
input element in UAs that support datalist.
The placeholder attribute represents a
short hint (a word or short phrase) intended to aid the user with data entry when the
control has no value. A hint could be a sample value or a brief description of the expected
format. The attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or
U+000D CARRIAGE RETURN (CR) characters.
The placeholder attribute should not be used as a
replacement for a label. For a longer hint or other advisory text, place the text
next to the control.
Use of the placeholder
attribute as a replacement for a label can reduce the
accessibility and usability of the control for a range of users including older
users and users with cognitive, mobility, fine motor skill or vision impairments.
While the hint given by the control's label is shown at all times, the short
hint given in the placeholder
attribute is only shown before the user enters a value. Furthermore,
placeholder text may be mistaken for
a pre-filled value, and as commonly implemented the default color of the placeholder text
provides insufficient contrast and the lack of a separate visible label
reduces the size of the hit region available for setting focus on the control.
These mechanisms are very similar but subtly different: the hint given by the
control's label is shown at all times; the short hint given in the placeholder attribute is shown before the user enters a
value; and the hint in the title attribute is shown when the user
requests further help.
User agents should present this hint to the user, after having stripped line breaks from it, when the element's value is the empty string, especially if the control is not focused.
If a user agent normally doesn't show this hint to the user when the control is
focused, then the user agent should nonetheless show the hint for the control if it
was focused as a result of the autofocus attribute, since
in that case the user will not have had an opportunity to examine the control before focusing
it.
Here is an example of a mail configuration user interface that uses the placeholder attribute:
<fieldset>
<legend>Mail Account</legend>
<p><label>Name: <input type="text" name="fullname" placeholder="John Ratzenberger"></label></p>
<p><label>Address: <input type="email" name="address" placeholder="john@example.net"></label></p>
<p><label>Password: <input type="password" name="password"></label></p>
<p><label>Description: <input type="text" name="desc" placeholder="My Email Account"></label></p>
</fieldset>
In situations where the control's content has one directionality but the placeholder needs to
have a different directionality, Unicode's bidirectional-algorithm formatting characters can be
used in the attribute value:
<input name=t1 type=tel placeholder="‫ رقم الهاتف 1 ‮">
<input name=t2 type=tel placeholder="‫ رقم الهاتف 2 ‮">
For slightly more clarity, here's the same example using numeric character references instead of inline Arabic:
<input name=t1 type=tel placeholder="‫رقم الهاتف 1‮">
<input name=t2 type=tel placeholder="‫رقم الهاتف 2‮">
Common input element APIs
- input .
value [ = value ] -
Returns the current value of the form control.
Can be set, to change the value.
Throws an InvalidStateError exception if it is set to any value other than the
empty string when the control is a file upload control.
- input .
checked [ = value ] -
Returns the current checkedness of the form
control.
Can be set, to change the checkedness.
- input .
files -
Returns a FileList object listing the selected files of the form control.
Returns null if the control isn't a file control.
- input .
valueAsDate [ = value ] -
Returns a Date object representing the form control's value, if applicable; otherwise, returns null.
Can be set, to change the value.
Throws an InvalidStateError exception if the control isn't date- or
time-based.
- input .
valueAsNumber [ = value ] -
Returns a number representing the form control's value,
if applicable; otherwise, returns NaN.
Can be set, to change the value. Setting this to NaN will set the underlying value to the
empty string.
Throws an InvalidStateError exception if the control is neither date- or
time-based nor numeric.
- input .
valueLow [ = value ] - input .
valueHigh [ = value ] -
Returns a number representing the low and high components of form control's value respectively, if applicable; otherwise, returns NaN.
Can be set, to change the value.
Throws an InvalidStateError exception if the control is not a two-handle range
control.
- input .
stepUp( [ n ] ) - input .
stepDown( [ n ] ) -
Changes the form control's value by the value given in
the step attribute, multiplied by n.
The default value for n is 1.
Throws InvalidStateError exception if the control is neither date- or time-based
nor numeric, or if the step attribute's value is "any".
- input .
list -
Returns the datalist element indicated by the list attribute.
The value IDL attribute allows scripts to
manipulate the value of an input element. The
attribute is in one of the following modes, which define its behaviour:
- value
-
On getting, it must return the current value of the
element. On setting, it must set the element's value to
the new value, set the element's dirty value
flag to true, invoke the value sanitization algorithm, if the element's
type attribute's current state defines one, and then, if
the element has a text entry cursor position, should move the text entry cursor position to the
end of the text field, unselecting any selected text and resetting the selection direction to
none.
- default
-
On getting, if the element has a value attribute, it
must return that attribute's value; otherwise, it must return the empty string. On setting, it
must set the element's value attribute to the new
value.
- default/on
-
On getting, if the element has a value attribute, it
must return that attribute's value; otherwise, it must return the string "on". On setting, it must set the element's value attribute to the new value.
- filename
-
On getting, it must return the string "C:\fakepath\" followed by the
name of the first file in the list of selected
files, if any, or the empty string if the list is empty. On setting, if the new value is
the empty string, it must empty the list of selected files; otherwise, it must throw an
InvalidStateError exception.
This "fakepath" requirement is a sad accident of history. See the example in the File Upload state section for more
information.
Since path components are not
permitted in file names in the list of selected
files, the "\fakepath\" cannot be mistaken for a path component.
The checked IDL attribute allows scripts to
manipulate the checkedness of an input
element. On getting, it must return the current checkedness of the element; and on setting, it must set the
element's checkedness to the new value and set the
element's dirty checkedness flag to
true.
The files IDL attribute allows scripts to
access the element's selected files. On
getting, if the IDL attribute applies, it must return a
FileList object that represents the current selected files. The same object must be returned
until the list of selected files changes. If
the IDL attribute does not apply, then it must instead return
null. [[!FILEAPI]]
The valueAsDate IDL attribute represents
the value of the element, interpreted as a date.
On getting, if the valueAsDate attribute does not apply, as defined for the input element's type attribute's current state, then return null. Otherwise, run
the algorithm to convert a string to a
Date object defined for that state to the element's value; if the algorithm returned a Date object, then
return it, otherwise, return null.
On setting, if the valueAsDate attribute does not apply, as defined for the input element's type attribute's current state, then throw an
InvalidStateError exception; otherwise, if the new value is null or a
Date object representing the NaN time value, then set the value of the element to the empty string; otherwise, run the
algorithm to convert a Date object to
a string, as defined for that state, on the new value, and set the value of the element to the resulting string.
The valueAsNumber IDL attribute
represents the value of the element, interpreted as a
number.
On getting, if the valueAsNumber attribute does not apply, as defined for the input element's type attribute's current state, then return a Not-a-Number (NaN)
value. Otherwise, if the valueAsDate
attribute applies, run the algorithm to convert a string to a Date
object defined for that state to the element's value; if the algorithm returned a Date object, then
return the time value of the object (the number of milliseconds from midnight UTC the
morning of 1970-01-01 to the time represented by the Date object), otherwise, return
a Not-a-Number (NaN) value. Otherwise, run the algorithm to convert a string to a number
defined for that state to the element's value; if the
algorithm returned a number, then return it, otherwise, return a Not-a-Number (NaN) value.
On setting, if the new value is infinite, then throw a TypeError exception.
Otherwise, if the valueAsNumber attribute does not apply, as defined for the input element's type attribute's current state, then throw an
InvalidStateError exception. Otherwise, if the new value is a Not-a-Number (NaN)
value, then set the value of the element to the empty
string. Otherwise, if the valueAsDate
attribute applies, run the algorithm to convert a Date object to a
string defined for that state, passing it a Date object whose time
value is the new value, and set the value of the
element to the resulting string. Otherwise, run the algorithm to convert a number to a string, as
defined for that state, on the new value, and set the value
of the element to the resulting string.
The valueLow and valueHigh IDL attributes represent the value of the element, interpreted as a comma-separated pair of
numbers.
On getting, if the attributes do not apply, as defined for the input
element's type attribute's current state, then return zero;
otherwise, run the following steps:
Let values be the values of
the element, interpreted according to the algorithm to convert a string to a number, as
defined by the input element's type
attribute's current state.
If the attribute in question is valueLow, return
the lowest of the values in values; otherwise, return the highest of the
values in values.
On setting, if the attributes do not apply, as defined for the input
element's type attribute's current state, then throw an
InvalidStateError exception. Otherwise, run the following steps:
Let values be the values of
the element, interpreted according to the algorithm to convert a string to a number, as
defined by the input element's type
attribute's current state.
Let new value be the result of running the algorithm to convert a number to a string, as
defined for that state, on the new value.
If the attribute in question is valueLow, replace
the lower value in values with new value; otherwise,
replace the higher value in values with new
value.
Sort values in increasing numeric order.
Let values be the result of running the algorithm to convert a number to a string, as
defined by the input element's type
attribute's current state, to the values in values.
Set the element's value to the concatenation of the
strings in in values, separating each value from the next
by a U+002C COMMA character (,).
The stepDown(n) and stepUp(n) methods, when invoked,
must run the following algorithm:
If the stepDown() and stepUp() methods do not apply, as defined for the
input element's type attribute's current state,
then throw an InvalidStateError exception, and abort these steps.
If the element has no allowed value step, then
throw an InvalidStateError exception, and abort these steps.
If the element has a minimum and a maximum and the minimum
is greater than the maximum, then abort these steps.
If the element has a minimum and a maximum and there is no value greater than or equal to the
element's minimum and less than or equal to the element's
maximum that, when subtracted from the step base, is an integral multiple of the allowed value step, then abort these steps.
If applying the algorithm to convert a
string to a number to the string given by the element's value does not result in an error, then let value be the result of that algorithm. Otherwise, let value
be zero.
-
If value subtracted from the step
base is not an integral multiple of the allowed value
step, then set value to the nearest value that, when subtracted from
the step base, is an integral multiple of the allowed value step, and that is less than value if the method invoked was the stepDown() and more than value
otherwise.
Otherwise (value subtracted from the step base is an integral multiple of the allowed value step), run the following substeps:
Let n be the argument.
Let delta be the allowed value
step multiplied by n.
If the method invoked was the stepDown() method,
negate delta.
Let value be the result of adding delta to value.
If the element has a minimum, and value is less than that minimum, then set
value to the smallest value that, when subtracted from the step base, is an integral multiple of the allowed value step, and that is more than or equal to minimum.
If the element has a maximum, and value is greater than that maximum, then
set value to the largest value that, when subtracted from the step base, is an integral multiple of the allowed value step, and that is less than or equal to maximum.
Let value as string be the result of running the algorithm to convert a number to a string, as
defined for the input element's type
attribute's current state, on value.
Set the value of the element to value
as string.
The list IDL attribute must return the current
suggestions source element, if any, or null otherwise.
Common event behaviours
When the input and change events apply
(which is the case for all input controls other than buttons and those with the type attribute in the Hidden state), the events are fired to indicate that the
user has interacted with the control. The input
event fires whenever the user has modified the data of the control. The change event fires when the value is committed, if
that makes sense for the control, or else when the control loses focus. In all cases, the input event comes before the corresponding change event (if any).
When an input element has a defined activation behaviour, the rules
for dispatching these events, if they apply, are given
in the section above that defines the type attribute's
state. (This is the case for all input controls with the type attribute in the Checkbox state, the Radio Button state, or the File Upload state.)
For input elements without a defined activation behaviour, but to
which these events apply, and for which the user
interface involves both interactive manipulation and an explicit commit action, then when the user
changes the element's value, the user agent must
queue a task to fire a simple event that bubbles named input at the input element, and any time the user
commits the change, the user agent must queue a task to fire a simple
event that bubbles named change at the
input element.
An example of a user interface involving both interactive manipulation and a
commit action would be a Range controls that use a
slider, when manipulated using a pointing device. While the user is dragging the control's knob,
input events would fire whenever the position changed,
whereas the change event would only fire when the user
let go of the knob, committing to a specific value.
For input elements without a defined activation behaviour, but to
which these events apply, and for which the user
interface involves an explicit commit action but no intermediate manipulation, then any time the
user commits a change to the element's value, the user
agent must queue a task to first fire a simple event that bubbles named
input at the input element, and then
fire a simple event that bubbles named change at the input element.
An example of a user interface with a commit action would be a Colour control that consists of a single button that brings
up a colour wheel: if the value only changes when the dialog
is closed, then that would be the explicit commit action. On the other hand, if manipulating the
control changes the colour interactively, then there might be no commit action.
Another example of a user interface with a commit action would be a Date control that allows both text-based user input and user
selection from a drop-down calendar: while text input might not have an explicit commit step,
selecting a date from the drop down calendar and then dismissing the drop down would be a commit
action.
For input elements without a defined activation behaviour, but to
which these events apply, any time the user causes the
element's value to change without an explicit commit
action, the user agent must queue a task to fire a simple event that
bubbles named input at the input element. The
corresponding change event, if any, will be fired when
the control loses focus.
Examples of a user changing the element's value would include the user typing into a text field, pasting a
new value into the field, or undoing an edit in that field. Some user interactions do not cause
changes to the value, e.g. hitting the "delete" key in an empty text field, or replacing some text
in the field with text from the clipboard that happens to be exactly the same text.
A Range control in the form of a
slider that the user has focused and is interacting with using a keyboard would be
another example of the user changing the element's value
without a commit step.
In the case of tasks that just fire an input event, user agents may wait for a suitable break in the
user's interaction before queuing the tasks; for example, a
user agent could wait for the user to have not hit a key for 100ms, so as to only fire the event
when the user pauses, instead of continuously for each keystroke.
When the user agent is to change an input element's value on behalf of the user (e.g. as part of a form prefilling
feature), the user agent must queue a task to first update the value accordingly, then fire a simple event that
bubbles named input at the input element,
then fire a simple event that bubbles named change at the input element.
These events are not fired in response to changes made to the values of form
controls by scripts. (This is to make it easier to update the values of form controls in response
to the user manipulating the controls, without having to then filter out the script's own changes
to avoid an infinite loop.)
The task source for these tasks is the
user interaction task source.
The button element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- Listed, labelable, submittable, and reassociateable form-associated element.
- Palpable content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but there must be no interactive content descendant.
- Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
autofocus — Automatically focus the form control when the page is loadeddisabled — Whether the form control is disabledform — Associates the control with a form elementformaction — URL to use for form submissionformenctype — Form data set encoding type to use for form submissionformmethod — HTTP method to use for form submissionformnovalidate — Bypass form control validation for form submissionformtarget — Browsing context for form submission- — Specifies the element's
name — Name of form control to use for form submission and in the form.elements API type — Type of buttonvalue — Value to be used for form submission- Allowed ARIA role attribute values:
button
(default - do not set),
link,
menuitem,
menuitemcheckbox,
menuitemradio
or radio.- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
interface HTMLButtonElement : HTMLElement {
attribute boolean autofocus;
attribute boolean disabled;
readonly attribute HTMLFormElement? form;
attribute DOMString formAction;
attribute DOMString formEnctype;
attribute DOMString formMethod;
attribute boolean formNoValidate;
attribute DOMString formTarget;
attribute DOMString name;
attribute DOMString type;
attribute DOMString value;
attribute ? ;
readonly attribute boolean willValidate;
readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
boolean reportValidity();
void setCustomValidity(DOMString error);
readonly attribute NodeList labels;
};
The button element represents a button labeled by its contents.
The element is a button.
The type attribute controls the behaviour of
the button when it is activated. It is an enumerated attribute. The following table
lists the keywords and states for the attribute — the keywords in the left column map to the
states in the cell in the second column on the same row as the keyword.
The missing value default is the Submit
Button state.
If the type attribute is in the Submit Button state, the element is specifically a
submit button.
Constraint validation: If the type
attribute is in the Reset Button state, the
Button state, or the state, the element is barred from constraint
validation.
When a button element is not disabled,
its activation behaviour element is to run the steps defined in the following list for
the current state of the element's type attribute:
- Submit Button
If the element has a form owner and the element's node document is
fully active, the element must submit the
form owner from the button element.
- Reset Button
If the element has a form owner and the element's node document is
fully active, the element must reset the
form owner.
- Button
Do nothing.
-
-
The element must follow these steps:
If the button is not being rendered, abort these
steps.
If the button element's node document is not fully
active, abort these steps.
Let menu be the element's , if
any. If there isn't one, then abort these steps.
Fire a trusted event with the name show at menu, using the RelatedEvent
interface, with the relatedTarget attribute
initialised to the button element. The event must be cancelable.
If the event is not canceled, then build and
show the menu for menu, with the button element as the
subject.
The form attribute is used to explicitly associate the
button element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and
to prevent its value from being submitted. The autofocus
attribute controls focus. The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes for form
submission.
The formnovalidate attribute can be
used to make submit buttons that do not trigger the constraint validation.
The formaction, formenctype, formmethod, formnovalidate, and formtarget must not be specified if the element's type attribute is not in the Submit Button state.
The value attribute gives the element's value
for the purposes of form submission. The element's value is
the value of the element's value attribute, if there is
one, or the empty string otherwise.
A button (and its value) is only included in the form submission if the button
itself was used to initiate the form submission.
If the element's type attribute is in the state, the attribute must be specified to give the element's
menu. The value must be the ID of a element in
the same home subtree whose attribute is in
the state. The attribute must not be specified if
the element's type attribute is not in the state.
A button element's is the first element in the
button's home subtree whose ID is that given by the button
element's attribute, if there is such an element and
its attribute is in the state; otherwise, the element has no .
The value and IDL attributes must reflect the
content attributes of the same name.
The type IDL attribute must
reflect the content attribute of the same name, limited to only known
values.
The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the
constraint validation API. The labels IDL
attribute provides a list of the element's labels. The autofocus, disabled, form, and name IDL attributes are
part of the element's forms API.
The following button is labeled "Show hint" and pops up a dialog box when activated:
<button type=button
onclick="alert('This 15-20 minute piece was composed by George Gershwin.')">
Show hint
</button>
The select element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- Listed, labelable, submittable, resettable, and reassociateable form-associated element.
- Palpable content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Zero or more
option, optgroup, and script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
autocomplete — Hint for form autofill featureautofocus — Automatically focus the form control when the page is loadeddisabled — Whether the form control is disabledform — Associates the control with a form elementmultiple — Whether to allow multiple valuesname — Name of form control to use for form submission and in the form.elements API required — Whether the control is required for form submissionsize — Size of the control- Allowed ARIA role attribute values:
listbox
(default - do not set) or
menu.- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
interface HTMLSelectElement : HTMLElement {
attribute DOMString autocomplete;
attribute boolean autofocus;
attribute boolean disabled;
readonly attribute HTMLFormElement? form;
attribute boolean multiple;
attribute DOMString name;
attribute boolean required;
attribute unsigned long size;
readonly attribute DOMString type;
readonly attribute HTMLOptionsCollection options;
attribute unsigned long length;
getter Element? item(unsigned long index);
HTMLOptionElement? namedItem(DOMString name);
void add((HTMLOptionElement or HTMLOptGroupElement) element, optional (HTMLElement or long)? before = null);
void remove(); // ChildNode overload
void remove(long index);
setter creator void (unsigned long index, HTMLOptionElement? option);
readonly attribute HTMLCollection selectedOptions;
attribute long selectedIndex;
attribute DOMString value;
readonly attribute boolean willValidate;
readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
boolean reportValidity();
void setCustomValidity(DOMString error);
readonly attribute NodeList labels;
};
The select element represents a control for selecting amongst a set of
options.
The multiple attribute is a boolean
attribute. If the attribute is present, then the select element
represents a control for selecting zero or more options from the list of options. If the attribute is absent, then the
select element represents a control for selecting a single option from
the list of options.
The size attribute gives the number of options
to show to the user. The size attribute, if specified, must
have a value that is a valid non-negative integer greater than zero.
The display size of a select element is the
result of applying the rules for parsing non-negative integers to the value of
element's size attribute, if it has one and parsing it is
successful. If applying those rules to the attribute's value is not successful, or if the size attribute is absent, then the element's display size is 4 if the element's multiple content attribute is present, and 1 otherwise.
The list of options for a select
element consists of all the option element children of the select
element, and all the option element children of all the optgroup element
children of the select element, in tree order.
The required attribute is a boolean
attribute. When specified, the user will be required to select a value before submitting
the form.
If a select element has a required
attribute specified, does not have a multiple attribute
specified, and has a display size of 1; and if the value of the first option element in the
select element's list of options (if
any) is the empty string, and that option element's parent node is the
select element (and not an optgroup element), then that
option is the select element's placeholder label option.
If a select element has a required
attribute specified, does not have a multiple attribute
specified, and has a display size of 1, then the
select element must have a placeholder label option.
Constraint validation: If the element has its required attribute specified, and either none of the
option elements in the select element's list of options have their selectedness set to true, or the only
option element in the select element's list of options with its selectedness set to true is the placeholder label
option, then the element is suffering from being missing.
If the multiple attribute is absent, and the element
is not disabled, then the user agent should allow the
user to pick an option element in its list
of options that is itself not disabled. Upon
this option element being picked (either
through a click, or through unfocusing the element after changing its value, or through a menu command, or through any other mechanism), and before the
relevant user interaction event is queued (e.g. before the
click event), the user agent must set the selectedness of the picked option element
to true, set its dirtiness to true, and then
send select update notifications.
If the multiple attribute is absent, whenever an
option element in the select element's list of options has its selectedness set to true, and whenever an
option element with its selectedness set to true is added to the
select element's list of options,
the user agent must set the selectedness of all
the other option elements in its list of
options to false.
If the multiple attribute is absent and the
element's display size is greater than 1, then the user
agent should also allow the user to request that the option whose selectedness is true, if any, be unselected. Upon this
request being conveyed to the user agent, and before the relevant user interaction event is queued (e.g. before the click event), the user agent must set the selectedness of that option element to
false, set its dirtiness to true, and then
send select update notifications.
If nodes are inserted or nodes are removed causing the list of options to gain or lose one or more
option elements, or if an option element in the list of options asks for
a reset, then, if the select element's multiple attribute is absent, the user agent must run the
first applicable set of steps from the following list:
- If the
select
element's display size is 1, and no option
elements in the select element's list of
options have their selectedness set to
true Set the selectedness of the first
option element in the list of
options in tree order that is not disabled, if any, to true.
- If two or more
option elements in the select element's list of options have their selectedness set to true Set the selectedness of all but the last
option element with its selectedness set to true in the list of options in tree order to
false.
If the multiple attribute is present, and the
element is not disabled, then the user agent should
allow the user to toggle the selectedness of the option elements in
its list of options that are themselves not disabled. Upon such an element being toggled (either through a click, or through a menu command, or any other mechanism), and before the relevant user
interaction event is queued (e.g. before a related click event), the selectedness of the option element must
be changed (from true to false or false to true), the dirtiness of the element must be set to true, and the
user agent must send select update notifications.
When the user agent is to send select update notifications, queue
a task to first fire a simple event that bubbles named input at the select element, and then fire a simple
event that bubbles named change at the
select element, using the user interaction task source as the task
source. If the stack of script settings objects was not empty when the user agent was
to send select update notifications, then the resulting input and change events must not be
trusted.
The reset algorithm for select
elements is to go through all the option elements in the element's list of options, set their selectedness to true if the option
element has a selected attribute, and false otherwise,
set their dirtiness to false, and then have the
option elements ask for a reset.
The form attribute is used to explicitly associate the select element with its form owner.
The name attribute represents the element's name.
The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted.
The autofocus attribute controls focus.
The autocomplete attribute controls how the user agent provides autofill behaviour.
A select element that is not disabled is
mutable.
- select .
type -
Returns "select-multiple" if the element has a multiple attribute, and "select-one"
otherwise.
- select .
options -
Returns an HTMLOptionsCollection of the list of options.
- select .
length [ = value ] -
Returns the number of elements in the list of
options.
When set to a smaller number, truncates the number of option elements in the
select.
When set to a greater number, adds new blank option elements to the
select.
- element = select .
item(index) - select[index]
-
Returns the item with index index from the list of options. The items are sorted in tree
order.
- element = select .
namedItem(name) -
Returns the first item with ID or name name from the list of options.
Returns null if no element with that ID could be found.
- select .
add(element [, before ] ) -
Inserts element before the node given by before.
The before argument can be a number, in which case element is inserted before the item with that number, or an element from the
list of options, in which case element is inserted before that element.
If before is omitted, null, or a number out of range, then element will be added at the end of the list.
This method will throw a HierarchyRequestError exception if element is an ancestor of the element into which it is to be inserted.
- select .
selectedOptions -
Returns an HTMLCollection of the list
of options that are selected.
- select .
selectedIndex [ = value ] -
Returns the index of the first selected item, if any, or −1 if there is no selected
item.
Can be set, to change the selection.
- select .
value [ = value ] -
Returns the value of the first selected item, if
any, or the empty string if there is no selected item.
Can be set, to change the selection.
The type IDL attribute, on getting, must
return the string "select-one" if the multiple attribute is absent, and the string "select-multiple" if the multiple
attribute is present.
The options IDL attribute must return an
HTMLOptionsCollection rooted at the select node, whose filter matches
the elements in the list of options.
The options collection is also mirrored on the
HTMLSelectElement object. The supported property indices at any instant
are the indices supported by the object returned by the options attribute at that instant.
The length IDL attribute must return the
number of nodes represented by the options collection. On setting, it must act like the attribute
of the same name on the options collection.
The item(index) method
must return the value returned by the method of the same
name on the options collection, when invoked with
the same argument.
The namedItem(name)
method must return the value returned by the
method of the same name on the options collection,
when invoked with the same argument.
When the user agent is to set the value of a new indexed
property for a given property index index to a new value value, it must instead set the
value of a new indexed property with the given property index index to
the new value value on the options
collection.
Similarly, the add() method must act like its
namesake method on that same options collection.
The remove() method must act like its
namesake method on that same options collection when it
has arguments, and like its namesake method on the ChildNode interface implemented by
the HTMLSelectElement ancestor interface Element when it has no
arguments.
The selectedOptions IDL attribute
must return an HTMLCollection rooted at the select node, whose filter
matches the elements in the list of options that
have their selectedness set to true.
The selectedIndex IDL attribute, on
getting, must return the index of the first
option element in the list of
options in tree order that has its selectedness set to true, if any. If there isn't one,
then it must return −1.
On setting, the selectedIndex attribute must set
the selectedness of all the option
elements in the list of options to false, and
then the option element in the list of
options whose index is the given new value, if
any, must have its selectedness set to true and
its dirtiness set to true.
This can result in no element having a selectedness set to true even in the case of the
select element having no multiple
attribute and a display size of 1.
The value IDL attribute, on getting, must
return the value of the first option
element in the list of options in tree
order that has its selectedness set to
true, if any. If there isn't one, then it must return the empty string.
On setting, the value attribute must set the selectedness of all the option elements
in the list of options to false, and then the
first option element in the list of
options, in tree order, whose value
is equal to the given new value, if any, must have its selectedness set to true and its dirtiness set to true.
This can result in no element having a selectedness set to true even in the case of the
select element having no multiple
attribute and a display size of 1.
The multiple, required, and size IDL attributes must reflect the
respective content attributes of the same name. The size IDL
attribute has a default value of zero.
For historical reasons, the default value of the size IDL attribute does not return the actual size used, which, in
the absence of the size content attribute, is either 1 or 4
depending on the presence of the multiple
attribute.
The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the
constraint validation API. The labels IDL
attribute provides a list of the element's labels. The autofocus, disabled, form, and name IDL attributes are
part of the element's forms API.
The following example shows how a select element can be used to offer the user
with a set of options from which the user can select a single option. The default option is
preselected.
<p>
<label for="unittype">Select unit type:</label>
<select id="unittype" name="unittype">
<option value="1"> Miner </option>
<option value="2"> Puffer </option>
<option value="3" selected> Snipey </option>
<option value="4"> Max </option>
<option value="5"> Firebot </option>
</select>
</p>
When there is no default option, a placeholder can be used instead:
<select name="unittype" required>
<option value=""> Select unit type </option>
<option value="1"> Miner </option>
<option value="2"> Puffer </option>
<option value="3"> Snipey </option>
<option value="4"> Max </option>
<option value="5"> Firebot </option>
</select>
Here, the user is offered a set of options from which he can select any number. By default,
all five options are selected.
<p>
<label for="allowedunits">Select unit types to enable on this map:</label>
<select id="allowedunits" name="allowedunits" multiple>
<option value="1" selected> Miner </option>
<option value="2" selected> Puffer </option>
<option value="3" selected> Snipey </option>
<option value="4" selected> Max </option>
<option value="5" selected> Firebot </option>
</select>
</p>
Sometimes, a user has to select one or more items. This example shows such an interface.
<p>Select the songs from that you would like on your Act II Mix Tape:</p>
<select multiple required name="act2">
<option value="s1">It Sucks to Be Me (Reprise)
<option value="s2">There is Life Outside Your Apartment
<option value="s3">The More You Ruv Someone
<option value="s4">Schadenfreude
<option value="s5">I Wish I Could Go Back to College
<option value="s6">The Money Song
<option value="s7">School for Monsters
<option value="s8">The Money Song (Reprise)
<option value="s9">There's a Fine, Fine Line (Reprise)
<option value="s10">What Do You Do With a B.A. in English? (Reprise)
<option value="s11">For Now
</select>
The datalist element
- Categories:
- Flow content.
- Phrasing content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Either: phrasing content.
- Or: Zero or more
option and script-supporting elements. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
- Allowed ARIA role attribute values:
listbox
(default - do not set).- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
interface HTMLDataListElement : HTMLElement {
readonly attribute HTMLCollection options;
};
The datalist element represents a set of option elements that
represent predefined options for other controls. In the rendering, the datalist
element represents nothing and it, along with its children, should
be hidden.
The datalist element can be used in two ways. In the simplest case, the
datalist element has just option element children.
<label>
Sex:
<input name=sex list=sexes>
<datalist id=sexes>
<option value="Female">
<option value="Male">
</datalist>
</label>
In the more elaborate case, the datalist element can be given contents that are to
be displayed for down-level clients that don't support datalist. In this case, the
option elements are provided inside a select element inside the
datalist element.
<label>
Sex:
<input name=sex list=sexes>
</label>
<datalist id=sexes>
<label>
or select from the list:
<select name=sex>
<option value="">
<option>Female
<option>Male
</select>
</label>
</datalist>
The datalist element is hooked up to an input element using the list attribute on the input element.
Each option element that is a descendant of the datalist element,
that is not disabled, and whose value is a string that isn't the empty string, represents a
suggestion. Each suggestion has a value and a label.
- datalist .
options -
Returns an HTMLCollection of the option elements of the
datalist element.
The options IDL attribute must return an
HTMLCollection rooted at the datalist node, whose filter matches
option elements.
Constraint validation: If an element has a datalist element
ancestor, it is barred from constraint validation.
The optgroup element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
select element. - Content model:
- Zero or more
option and script-supporting elements. - Tag omission in text/html:
- An
optgroup element's end tag can be omitted
if the optgroup element is
immediately followed by another optgroup element, or if there is no more content in
the parent element. - Content attributes:
- Global attributes
disabled — Whether the form control is disabledlabel — User-visible label- Allowed ARIA role attribute values:
- None
- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLOptGroupElement : HTMLElement {
attribute boolean disabled;
attribute DOMString label;
};
The optgroup element represents a group of option
elements with a common label.
The element's group of option elements consists of the option
elements that are children of the optgroup element.
When showing option elements in select elements, user agents should
show the option elements of such groups as being related to each other and separate
from other option elements.
The disabled attribute is a
boolean attribute and can be used to disable a group of option elements
together.
The label attribute must be specified. Its
value gives the name of the group, for the purposes of the user interface. User
agents should use this attribute's value when labeling the group of option elements
in a select element.
The disabled and label attributes must reflect the
respective content attributes of the same name.
There is no way to select an optgroup element. Only
option elements can be selected. An optgroup element merely provides a
label for a group of option elements.
The following snippet shows how a set of lessons from three courses could be offered in a
select drop-down widget:
<form action="courseselector.dll" method="get">
<p>Which course would you like to watch today?
<p><label>Course:
<select name="c">
<optgroup label="8.01 Physics I: Classical Mechanics">
<option value="8.01.1">Lecture 01: Powers of Ten
<option value="8.01.2">Lecture 02: 1D Kinematics
<option value="8.01.3">Lecture 03: Vectors
<optgroup label="8.02 Electricity and Magnestism">
<option value="8.02.1">Lecture 01: What holds our world together?
<option value="8.02.2">Lecture 02: Electric Field
<option value="8.02.3">Lecture 03: Electric Flux
<optgroup label="8.03 Physics III: Vibrations and Waves">
<option value="8.03.1">Lecture 01: Periodic Phenomenon
<option value="8.03.2">Lecture 02: Beats
<option value="8.03.3">Lecture 03: Forced Oscillations with Damping
</select>
</label>
<p><input type=submit value="▶ Play">
</form>
The option element
- Categories:
- None.
- Contexts in which this element can be used:
- As a child of a
select element. - As a child of a
datalist element. - As a child of an
optgroup element. - Content model:
- If the element has a
label attribute and a value attribute: Nothing. - If the element has a
label attribute but no value attribute: Text. - If the element has no
label attribute: Text that is not inter-element whitespace. - Tag omission in text/html:
- An
option element's end tag can be omitted if
the option element is immediately followed by another option element, or
if it is immediately followed by an optgroup element, or if there is no more content
in the parent element. - Content attributes:
- Global attributes
disabled — Whether the form control is disabledlabel — User-visible labelselected — Whether the option is selected by defaultvalue — Value to be used for form submission- Allowed ARIA role attribute values:
option
(default - do not set),
menuitem,
menuitemradio
or separator.- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
[NamedConstructor=Option(optional DOMString text = "", optional DOMString value, optional boolean defaultSelected = false, optional boolean selected = false)]
interface HTMLOptionElement : HTMLElement {
attribute boolean disabled;
readonly attribute HTMLFormElement? form;
attribute DOMString label;
attribute boolean defaultSelected;
attribute boolean selected;
attribute DOMString value;
attribute DOMString text;
readonly attribute long index;
};
The option element represents an option in a select
element or as part of a list of suggestions in a datalist element.
In certain circumstances described in the definition of the select element, an
option element can be a select element's placeholder label
option. A placeholder label option does not represent an actual option, but
instead represents a label for the select control.
The disabled attribute is a boolean
attribute. An option element is disabled if its disabled attribute is present or if it is a child of an
optgroup element whose disabled attribute
is present.
An option element that is disabled must
prevent any click events that are queued on the user interaction task source from being dispatched on the
element.
The label attribute provides a label for
element. The label of an option element is
the value of the label content attribute, if there is one and its value is not the empty string,
or, otherwise, the value of the element's text IDL
attribute.
The label content attribute, if specified, must not be
empty.
The value attribute provides a value for
element. The value of an option element is
the value of the value content attribute, if there is one,
or, if there is not, the value of the element's text IDL
attribute.
The selected attribute is a boolean
attribute. It represents the default selectedness of the element.
The dirtiness of an option element is
a boolean state, initially false. It controls whether adding or removing the selected content attribute has any effect.
The selectedness of an option
element is a boolean state, initially false. Except where otherwise specified, when the element is
created, its selectedness must be set to true if
the element has a selected attribute. Whenever an
option element's selected attribute is
added, if its dirtiness is false, its selectedness must be set to true. Whenever an
option element's selected attribute is
removed, if its dirtiness is false, its
selectedness must be set to false.
The Option() constructor, when called with three
or fewer arguments, overrides the initial state of the selectedness state to always be false even if the third
argument is true (implying that a selected attribute is
to be set). The fourth argument can be used to explicitly set the initial selectedness state when using the constructor.
A select element whose multiple
attribute is not specified must not have more than one descendant option element with
its selected attribute set.
An option element's index is the number of
option elements that are in the same list of
options but that come before it in tree order. If the option
element is not in a list of options, then the
option element's index is zero.
- option .
selected -
Returns true if the element is selected, and false otherwise.
Can be set, to override the current state of the element.
- option .
index -
Returns the index of the element in its select element's options list.
- option .
form -
Returns the element's form element, if any, or null otherwise.
- option .
text -
Same as textContent, except that spaces are collapsed and script elements are skipped.
- option = new
Option( [ text [, value [, defaultSelected [, selected ] ] ] ] ) -
Returns a new option element.
The text argument sets the contents of the element.
The value argument sets the value
attribute.
The defaultSelected argument sets the selected attribute.
The selected argument sets whether or not the element is selected. If it
is omitted, even if the defaultSelected argument is true, the element is not
selected.
The disabled IDL attribute must
reflect the content attribute of the same name. The defaultSelected IDL attribute must
reflect the selected content attribute.
The label IDL attribute, on getting, if there
is a label content attribute, must return that attribute's
value; otherwise, it must return the element's label.
On setting, the element's label content attribute must be
set to the new value.
The value IDL attribute, on getting, must
return the element's value. On setting, the element's
value content attribute must be set to the new value.
The selected IDL attribute, on getting,
must return true if the element's selectedness
is true, and false otherwise. On setting, it must set the element's selectedness to the new value, set its dirtiness to true, and then cause the element to
ask for a reset.
The index IDL attribute must return the
element's index.
The text IDL attribute, on getting, must
return the result of stripping and collapsing
whitespace from the concatenation of data of all the
Text node descendants of the option element, in tree order,
excluding any that are descendants of descendants of the option element that are
themselves script elements in the HTML namespace or script elements in the SVG namespace.
On setting, the text attribute must act as if the
textContent IDL attribute on the element had been set to the new value.
The form IDL attribute's behaviour depends on
whether the option element is in a select element or not. If the
option has a select element as its parent, or has an
optgroup element as its parent and that optgroup element has a
select element as its parent, then the form IDL
attribute must return the same value as the form IDL attribute
on that select element. Otherwise, it must return null.
A constructor is provided for creating HTMLOptionElement objects (in addition to
the factory methods from DOM such as createElement()): Option(text, value, defaultSelected, selected). When invoked as a
constructor, it must return a new HTMLOptionElement object (a new option
element). If the first argument is not the empty string, the new object must have as its only
child a Text node whose data is the value of that argument. Otherwise, it must have
no children. If the value argument is present, the new object must have a
value attribute set with the value of the argument as its
value. If the defaultSelected argument is true, the new object must have a
selected attribute set with no value. If the selected argument is true, the new object must have its selectedness set to true; otherwise the selectedness must be set to false, even if the defaultSelected argument is true. The element's node document must be the active
document of the browsing context of the Window object on which
the interface object of the invoked constructor is found.
The textarea element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- Listed, labelable, submittable, resettable, and reassociateable form-associated element.
- Palpable content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Text.
- Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
autocomplete — Hint for form autofill featureautofocus — Automatically focus the form control when the page is loadedcols — Maximum number of characters per linedirname — Name of form field to use for sending the element's directionality in form submissiondisabled — Whether the form control is disabledform — Associates the control with a form elementinputmode — Hint for selecting an input modalitymaxlength — Maximum length of valueminlength — Minimum length of valuename — Name of form control to use for form submission and in the form.elements API placeholder — User-visible label to be placed within the form controlreadonly — Whether to allow the value to be edited by the userrequired — Whether the control is required for form submissionrows — Number of lines to showwrap — How the value of the form control is to be wrapped for form submission- Allowed ARIA role attribute values:
textbox
(default - do not set).- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
interface HTMLTextAreaElement : HTMLElement {
attribute DOMString autocomplete;
attribute boolean autofocus;
attribute unsigned long cols;
attribute DOMString dirName;
attribute boolean disabled;
readonly attribute HTMLFormElement? form;
attribute DOMString inputMode;
attribute long maxLength;
attribute long minLength;
attribute DOMString name;
attribute DOMString placeholder;
attribute boolean readOnly;
attribute boolean required;
attribute unsigned long rows;
attribute DOMString wrap;
readonly attribute DOMString type;
attribute DOMString defaultValue;
[TreatNullAs=EmptyString] attribute DOMString value;
readonly attribute unsigned long textLength;
readonly attribute boolean willValidate;
readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
boolean reportValidity();
void setCustomValidity(DOMString error);
readonly attribute NodeList labels;
void select();
attribute unsigned long selectionStart;
attribute unsigned long selectionEnd;
attribute DOMString selectionDirection;
void setRangeText(DOMString replacement);
void setRangeText(DOMString replacement, unsigned long start, unsigned long end, optional SelectionMode selectionMode = "preserve");
void setSelectionRange(unsigned long start, unsigned long end, optional DOMString direction);
};
The textarea element represents a multiline plain text edit
control for the element's raw
value. The contents of the control represent the control's default value.
The raw value of a textarea
control must be initially the empty string.
This element has rendering requirements involving the
bidirectional algorithm.
The readonly attribute is a
boolean attribute used to control whether the text can be edited by the user or
not.
In this example, a text field is marked read-only because it represents a read-only file:
Filename: <code>/etc/bash.bashrc</code>
<textarea name="buffer" readonly>
# System-wide .bashrc file for interactive bash(1) shells.
# To enable the settings / commands in this file for login shells as well,
# this file has to be sourced in /etc/profile.
# If not running interactively, don't do anything
[ -z "$PS1" ] && return
...</textarea>
Constraint validation: If the readonly attribute is specified on a textarea
element, the element is barred from constraint validation.
A textarea element is mutable if it is
neither disabled nor has a readonly attribute specified.
When a textarea is mutable, its raw value should be editable by the user: the user agent
should allow the user to edit, insert, and remove text, and to insert and remove line breaks in
the form of U+000A LINE FEED (LF) characters. Any time the user causes the element's raw value to change, the user agent must queue a
task to fire a simple event that bubbles named input at the textarea element. User agents may wait for a
suitable break in the user's interaction before queuing the task; for example, a user agent could
wait for the user to have not hit a key for 100ms, so as to only fire the event when the user
pauses, instead of continuously for each keystroke.
A textarea element has a dirty value
flag, which must be initially set to false, and must be set to true whenever the user
interacts with the control in a way that changes the raw
value.
When the textarea element's textContent IDL attribute changes value,
if the element's dirty value flag is false, then the
element's raw value must be set to the value of
the element's textContent IDL attribute.
The reset algorithm for textarea
elements is to set the element's raw value to the
value of the element's textContent IDL attribute.
When a textarea element is popped off the stack of open elements of
an HTML parser or XML parser, then the user agent must invoke the
element's reset algorithm.
If the element is mutable, the user agent should allow
the user to change the writing direction of the element, setting it either to a left-to-right
writing direction or a right-to-left writing direction. If the user does so, the user agent must
then run the following steps:
Set the element's dir attribute to "ltr" if the user selected a left-to-right writing direction, and
"rtl" if the user selected a right-to-left writing
direction.
Queue a task to fire a simple event that bubbles named input at the textarea element.
The cols attribute specifies the expected
maximum number of characters per line. If the cols
attribute is specified, its value must be a valid non-negative integer greater than
zero. If applying the rules for parsing non-negative integers to
the attribute's value results in a number greater than zero, then the element's character width is that value; otherwise, it is
20.
The user agent may use the textarea element's character width as a hint to the user as to how many
characters the server prefers per line (e.g. for visual user agents by making the width of the
control be that many characters). In visual renderings, the user agent should wrap the user's
input in the rendering so that each line is no wider than this number of characters.
The rows attribute specifies the number of
lines to show. If the rows attribute is specified, its
value must be a valid non-negative integer greater than zero. If
applying the rules for parsing non-negative integers to the attribute's value results
in a number greater than zero, then the element's character
height is that value; otherwise, it is 2.
Visual user agents should set the height of the control to the number of lines given by character height.
The wrap attribute is an enumerated
attribute with two keywords and states: the soft keyword which maps to the Soft state, and the hard keyword which maps to the Hard state. The missing value default is the
Soft state.
The Soft state indicates that the text in the
textarea is not to be wrapped when it is submitted (though it can still be wrapped in
the rendering).
The Hard state indicates that the text in the
textarea is to have newlines added by the user agent so that the text is wrapped when
it is submitted.
If the element's wrap attribute is in the Hard state, the cols attribute must be specified.
For historical reasons, the element's value is normalised in three different ways for three
different purposes. The raw value is the value as
it was originally set. It is not normalized. The API
value is the value used in the value IDL
attribute. It is normalised so that line breaks use U+000A LINE FEED (LF) characters. Finally,
there is the value, as used in form submission and other
processing models in this specification. It is normalised so that line breaks use U+000D CARRIAGE
RETURN U+000A LINE FEED (CRLF) character pairs, and in addition, if necessary given the element's
wrap attribute, additional line breaks are inserted to
wrap the text at the given width.
The element's API value is defined to be the
element's raw value with the following
transformation applied:
Replace every U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair from the raw value with a single U+000A LINE FEED (LF)
character.
Replace every remaining U+000D CARRIAGE RETURN character from the raw value with a single U+000A LINE FEED (LF)
character.
The element's value is defined to be the element's raw value with the textarea wrapping
transformation applied. The textarea wrapping transformation is the following
algorithm, as applied to a string:
Replace every occurrence of a U+000D CARRIAGE RETURN (CR) character not followed by a
U+000A LINE FEED (LF) character, and every occurrence of a U+000A LINE FEED (LF) character not
preceded by a U+000D CARRIAGE RETURN (CR) character, by a two-character string consisting of a
U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair.
If the element's wrap attribute is in the Hard state, insert U+000D CARRIAGE RETURN U+000A
LINE FEED (CRLF) character pairs into the string using a UA-defined algorithm so that each line
has no more than character width characters. For
the purposes of this requirement, lines are delimited by the start of the string, the end of the
string, and U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pairs.
The maxlength attribute is a form control maxlength attribute controlled
by the textarea element's dirty value
flag.
If the textarea element has a maximum allowed value length, then the
element's children must be such that the code-unit length of the value of the
element's textContent IDL attribute with the textarea wrapping
transformation applied is equal to or less than the element's maximum allowed value
length.
The minlength attribute is a form control minlength attribute
controlled by the textarea element's dirty
value flag.
The required attribute is a
boolean attribute. When specified, the user will be required to enter a value before
submitting the form.
Constraint validation: If the element has its required attribute specified, and the element is mutable, and the element's value is the empty string, then the element is suffering
from being missing.
The placeholder attribute represents
a short hint (a word or short phrase) intended to aid the user with data entry when the
control has no value. A hint could be a sample value or a brief description of the expected
format.
The placeholder attribute should not be used as
an alternative to a label. For a longer hint or other advisory text, the title attribute is more appropriate.
These mechanisms are very similar but subtly different: the hint given by the
control's label is shown at all times; the short hint given in the placeholder attribute is shown before the user enters a
value; and the hint in the title attribute is shown when the user
requests further help.
User agents should present this hint to the user when the element's value is the empty string and the control is not
focused (e.g. by displaying it inside a blank unfocused control). All U+000D CARRIAGE
RETURN U+000A LINE FEED character pairs (CRLF) in the hint, as well as all other U+000D CARRIAGE
RETURN (CR) and U+000A LINE FEED (LF) characters in the hint, must be treated as line breaks when
rendering the hint.
The name attribute represents the element's name.
The dirname attribute controls how the element's directionality is submitted.
The disabled attribute is used to make the control
non-interactive and to prevent its value from being submitted.
The form attribute is used to explicitly associate the
textarea element with its form owner.
The autofocus attribute controls focus.
The inputmode attribute controls the user interface's input
modality for the control.
The autocomplete attribute controls how the user agent
provides autofill behaviour.
- textarea .
type -
Returns the string "textarea".
- textarea .
value -
Returns the current value of the element.
Can be set, to change the value.
The cols, placeholder, required, rows, and wrap attributes must reflect the
respective content attributes of the same name. The cols
and rows attributes are limited to only non-negative
numbers greater than zero. The cols attribute's
default value is 20. The rows attribute's default value is
2. The dirName IDL attribute must
reflect the dirname content attribute. The inputMode IDL attribute must
reflect the inputmode content attribute,
limited to only known values. The maxLength IDL attribute must
reflect the maxlength content attribute,
limited to only non-negative numbers. The minLength IDL attribute must
reflect the minlength content attribute,
limited to only non-negative numbers. The readOnly IDL attribute must reflect
the readonly content attribute.
The type IDL attribute must return the value
"textarea".
The defaultValue IDL attribute must
act like the element's textContent IDL attribute.
The value attribute must, on getting, return
the element's API value; on setting, it must set
the element's raw value to the new value, set the
element's dirty value flag to true, and should then
move the text entry cursor position to the end of the text field, unselecting any selected text
and resetting the selection direction to none.
The textLength IDL attribute must
return the code-unit length of the element's API value.
The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the
constraint validation API. The labels IDL
attribute provides a list of the element's labels. The select(), selectionStart, selectionEnd, selectionDirection, setRangeText(), and setSelectionRange() methods and IDL attributes
expose the element's text selection. The autofocus, disabled, form, and name IDL attributes are part of the element's forms API.
Here is an example of a textarea being used for unrestricted free-form text input
in a form:
<p>If you have any comments, please let us know: <textarea cols=80 name=comments></textarea></p>
To specify a maximum length for the comments, one can use the maxlength attribute:
<p>If you have any short comments, please let us know: <textarea cols=80 name=comments maxlength=200></textarea></p>
To give a default value, text can be included inside the element:
<p>If you have any comments, please let us know: <textarea cols=80 name=comments>You rock!</textarea></p>
You can also give a minimum length. Here, a letter needs to be filled out by the user; a
template (which is shorter than the minimum length) is provided, but is insufficient to submit
the form:
<textarea required minlength="500">Dear Madam Speaker,
Regarding your letter dated ...
...
Yours Sincerely,
...</textarea>
A placeholder can be given as well, to suggest the basic form to the user, without providing
an explicit template:
<textarea placeholder="Dear Francine,
They closed the parks this week, so we won't be able to
meet your there. Should we just have dinner?
Love,
Daddy"></textarea>
To have the browser submit the directionality of the element along with the
value, the dirname attribute can be specified:
<p>If you have any comments, please let us know (you may use either English or Hebrew for your comments):
<textarea cols=80 name=comments dirname=comments.dir></textarea></p>
The keygen element
- Categories:
- Flow content.
- Phrasing content.
- Interactive content.
- Listed, labelable, submittable, resettable, and reassociateable form-associated element.
- Palpable content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Nothing.
- Tag omission in text/html:
- No end tag.
- Content attributes:
- Global attributes
autofocus — Automatically focus the form control when the page is loadedchallenge — String to package with the generated and signed public keydisabled — Whether the form control is disabledform — Associates the control with a form elementkeytype — The type of cryptographic key to generatename — Name of form control to use for form submission and in the form.elements API - Allowed ARIA role attribute values:
- None
- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLKeygenElement : HTMLElement {
attribute boolean autofocus;
attribute DOMString challenge;
attribute boolean disabled;
readonly attribute HTMLFormElement? form;
attribute DOMString keytype;
attribute DOMString name;
readonly attribute DOMString type;
readonly attribute boolean willValidate;
readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
boolean reportValidity();
void setCustomValidity(DOMString error);
readonly attribute NodeList labels;
};
The keygen element represents a key pair generator control. When the
control's form is submitted, the private key is stored in the local keystore, and the public key
is packaged and sent to the server.
The challenge attribute may be specified.
Its value will be packaged with the submitted key.
The keytype attribute is an
enumerated attribute. The following table lists the keywords and states for the
attribute — the keywords in the left column map to the states listed in the cell in the
second column on the same row as the keyword. User agents are not required to support these
values, and must only recognise values whose corresponding algorithms they support.
The invalid value default state is the unknown state. The missing value default state is the RSA state, if it is supported, or the unknown state otherwise.
This specification does not specify what key types user agents are to support
— it is possible for a user agent to not support any key types at all.
The user agent may expose a user interface for each keygen element to allow the
user to configure settings of the element's key pair generator, e.g. the key length.
The reset algorithm for keygen
elements is to set these various configuration settings back to their defaults.
The element's value is the string returned from the
following algorithm:
-
Use the appropriate step from the following list:
- If the
keytype attribute is in the RSA state -
Generate an RSA key pair using the settings given by the user, if appropriate, using the
md5WithRSAEncryption RSA signature algorithm (the signature algorithm
with MD5 and the RSA encryption algorithm) referenced in section 2.2.1 ("RSA Signature
Algorithm") of RFC 3279, and defined in RFC 3447. [[!RFC3279]] [[!RFC3447]]
- Otherwise, the
keytype attribute is in the unknown state -
The given key type is not supported. Return the empty string and abort this algorithm.
Let private key be the generated private key.
Let public key be the generated public key.
Let signature algorithm be the selected signature algorithm.
-
If the element has a challenge attribute, then let
challenge be that attribute's value. Otherwise, let challenge be the empty string.
-
Let algorithm be an ASN.1 AlgorithmIdentifier
structure as defined by RFC 5280, with the algorithm field giving the
ASN.1 OID used to identify signature algorithm, using the OIDs defined in
section 2.2 ("Signature Algorithms") of RFC 3279, and the parameters field
set up as required by RFC 3279 for AlgorithmIdentifier structures for that
algorithm. [[!X690]] [[!RFC5280]] [[!RFC3279]]
-
Let spki be an ASN.1 SubjectPublicKeyInfo structure
as defined by RFC 5280, with the algorithm field set to the algorithm structure from the previous step, and the subjectPublicKey field set to the BIT STRING value resulting from ASN.1 DER
encoding the public key. [[!X690]] [[!RFC5280]]
-
Let publicKeyAndChallenge be an ASN.1 PublicKeyAndChallenge
structure as defined below, with the spki field set to the spki structure from the previous step, and the challenge
field set to the string challenge obtained earlier. [[!X690]]
-
Let signature be the BIT STRING value resulting from ASN.1 DER encoding
the signature generated by applying the signature algorithm to the byte
string obtained by ASN.1 DER encoding the publicKeyAndChallenge structure,
using private key as the signing key. [[!X690]]
-
Let signedPublicKeyAndChallenge be an ASN.1
SignedPublicKeyAndChallenge structure as defined below, with the publicKeyAndChallenge field set to the publicKeyAndChallenge
structure, the signatureAlgorithm field set to the algorithm structure, and the signature field set to the BIT
STRING signature from the previous step. [[!X690]]
-
Return the result of base64 encoding the result of ASN.1 DER encoding the signedPublicKeyAndChallenge structure. [[!RFC4648]] [[!X690]]
The data objects used by the above algorithm are defined as follows. These definitions use the
same "ASN.1-like" syntax defined by RFC 5280. [[!RFC5280]]
PublicKeyAndChallenge ::= SEQUENCE {
spki SubjectPublicKeyInfo,
challenge IA5STRING
}
SignedPublicKeyAndChallenge ::= SEQUENCE {
publicKeyAndChallenge PublicKeyAndChallenge,
signatureAlgorithm AlgorithmIdentifier,
signature BIT STRING
}
Constraint validation: The keygen element is barred from
constraint validation.
The form attribute is used to explicitly associate the
keygen element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and
to prevent its value from being submitted. The autofocus
attribute controls focus.
- keygen .
type -
Returns the string "keygen".
The challenge IDL attribute must
reflect the content attribute of the same name.
The keytype IDL attribute must
reflect the content attribute of the same name, limited to only known
values.
The type IDL attribute must return the value
"keygen".
The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the
constraint validation API. The labels IDL
attribute provides a list of the element's labels. The autofocus, disabled, form, and name IDL attributes are
part of the element's forms API.
This specification does not specify how the private key generated is to be used.
It is expected that after receiving the SignedPublicKeyAndChallenge (SPKAC)
structure, the server will generate a client certificate and offer it back to the user for
download; this certificate, once downloaded and stored in the key store along with the private
key, can then be used to authenticate to services that use TLS and certificate authentication. For
more information, see e.g. this MDN article.
To generate a key pair, add the private key to the user's key store, and submit the public key
to the server, markup such as the following can be used:
<form action="processkey.cgi" method="post" enctype="multipart/form-data">
<p><keygen name="key"></p>
<p><input type=submit value="Submit key..."></p>
</form>
The server will then receive a form submission with a packaged RSA public key as the value of
"key". This can then be used for various purposes, such as generating a
client certificate, as mentioned above.
The output element
- Categories:
- Flow content.
- Phrasing content.
- Listed, labelable, resettable, and reassociateable form-associated element.
- Palpable content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content.
- Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
for — Specifies controls from which the output was calculatedform — Associates the control with a form elementname — Name of form control to use in the form.elements API - Allowed ARIA role attribute values:
status
(default - do not set), any role value.- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
interface HTMLOutputElement : HTMLElement {
[PutForwards=value] readonly attribute DOMSettableTokenList htmlFor;
readonly attribute HTMLFormElement? form;
attribute DOMString name;
readonly attribute DOMString type;
attribute DOMString defaultValue;
attribute DOMString value;
readonly attribute boolean willValidate;
readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
boolean reportValidity();
void setCustomValidity(DOMString error);
readonly attribute NodeList labels;
};
The output element represents the result of a calculation performed
by the application, or the result of a user action.
This element can be contrasted with the samp element, which is the
appropriate element for quoting the output of other programs run previously.
The for content attribute allows an explicit
relationship to be made between the result of a calculation and the elements that represent the
values that went into the calculation or that otherwise influenced the calculation. The for attribute, if specified, must contain a string consisting of
an unordered set of unique space-separated tokens that are
case-sensitive, each of which must have the value of an ID of an element in the same Document.
The form attribute is used to explicitly associate the
output element with its form owner. The name attribute represents the element's name. The output
element is associated with a form so that it can be easily referenced from the event handlers of
form controls; the element's value itself is not submitted when the form is submitted.
The element has a value mode flag which is either value or default. Initially, the value mode flag must be set to default.
The element also has a default value.
Initially, the default value must be the empty
string.
When the value mode flag is in mode default, the contents of the element represent both
the value of the element and its default value.
When the value mode flag is in mode value, the contents of the element represent the
value of the element only, and the default value
is only accessible using the defaultValue IDL
attribute.
Whenever the element's descendants are changed in any way, if the value mode flag is in mode default, the element's default value must be set to the value of the
element's textContent IDL attribute.
The reset algorithm for output
elements is to set the element's value mode flag to default and then to set the element's
textContent IDL attribute to the value of the element's default value (thus replacing the element's child
nodes).
- output .
value [ = value ] -
Returns the element's current value.
Can be set, to change the value.
- output .
defaultValue [ = value ] -
Returns the element's current default value.
Can be set, to change the default value.
- output .
type -
Returns the string "output".
The value IDL attribute must act like the
element's textContent IDL attribute, except that on setting, in addition, before the
child nodes are changed, the element's value mode flag
must be set to value.
The defaultValue IDL attribute, on
getting, must return the element's default
value. On setting, the attribute must set the element's default value, and, if the element's value mode flag is in the mode default, set the element's textContent IDL
attribute as well.
The type attribute must return the string
"output".
The htmlFor IDL attribute must
reflect the for content attribute.
The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the
constraint validation API. The labels IDL
attribute provides a list of the element's labels. The form and name IDL attributes are
part of the element's forms API.
A simple calculator could use output for its display of calculated results:
<form onsubmit="return false" oninput="o.value = a.valueAsNumber + b.valueAsNumber">
<input name=a type=number step=any> +
<input name=b type=number step=any> =
<output name=o for="a b"></output>
</form>
In this example, an output element is used to report the results of a calculation performed by a remote
server, as they come in:
<output id="result"></output>
<script>
var primeSource = new WebSocket('ws://primes.example.net/');
primeSource.onmessage = function (event) {
document.getElementById('result').value = event.data;
}
</script>
The progress element
- Categories:
- Flow content.
- Phrasing content.
- Labelable element.
- Palpable content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but there must be no
progress element descendants. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
value — Current value of the elementmax — Upper bound of range- Allowed ARIA role attribute values:
progressbar
(default - do not set).- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
interface HTMLProgressElement : HTMLElement {
attribute double value;
attribute double max;
readonly attribute double position;
readonly attribute NodeList labels;
};
The progress element represents the completion progress of a task.
The progress is either indeterminate, indicating that progress is being made but that it is not
clear how much more work remains to be done before the task is complete (e.g. because the task is
waiting for a remote host to respond), or the progress is a number in the range zero to a maximum,
giving the fraction of work that has so far been completed.
There are two attributes that determine the current task completion represented by the element.
The value attribute specifies how much of the
task has been completed, and the max attribute
specifies how much work the task requires in total. The units are arbitrary and not specified.
To make a determinate progress bar, add a value attribute with the current progress (either a number from
0.0 to 1.0, or, if the max attribute is specified, a number
from 0 to the value of the max attribute). To make an
indeterminate progress bar, remove the value
attribute.
Authors are encouraged to also include the current value and the maximum value inline as text
inside the element, so that the progress is made available to users of legacy user agents.
Here is a snippet of a Web application that shows the progress of some automated task:
<section>
<h2>Task Progress</h2>
<p>Progress: <progress id="p" max=100><span>0</span>%</progress></p>
<script>
var progressBar = document.getElementById('p');
function updateProgress(newValue) {
progressBar.value = newValue;
progressBar.getElementsByTagName('span')[0].textContent = newValue;
}
</script>
</section>
(The updateProgress() method in this example would be called by some
other code on the page to update the actual progress bar as the task progressed.)
The value and max attributes, when present, must have values that are valid floating-point numbers. The value attribute, if present, must have a value equal to or
greater than zero, and less than or equal to the value of the max attribute, if present, or 1.0, otherwise. The max attribute, if present, must have a value greater than
zero.
The progress element is the wrong element to use for something that
is just a gauge, as opposed to task progress. For instance, indicating disk space usage using
progress would be inappropriate. Instead, the meter element is available
for such use cases.
User agent requirements: If the value
attribute is omitted, then the progress bar is an indeterminate progress bar. Otherwise, it is a
determinate progress bar.
If the progress bar is a determinate progress bar and the element has a max attribute, the user agent must parse the max attribute's value according to the rules for parsing
floating-point number values. If this does not result in an error, and if the parsed value
is greater than zero, then the maximum value of the
progress bar is that value. Otherwise, if the element has no max attribute, or if it has one but parsing it resulted in an
error, or if the parsed value was less than or equal to zero, then the maximum value of the progress bar is 1.0.
If the progress bar is a determinate progress bar, user agents must parse the value attribute's value according to the rules for
parsing floating-point number values. If this does not result in an error, and if the
parsed value is less than the maximum value and
greater than zero, then the current value of the
progress bar is that parsed value. Otherwise, if the parsed value was greater than or equal to the
maximum value, then the current value of the progress bar is the maximum value of the progress bar. Otherwise, if parsing
the value attribute's value resulted in an error, or a
number less than or equal to zero, then the current
value of the progress bar is zero.
UA requirements for showing the progress bar: When representing a
progress element to the user, the UA should indicate whether it is a determinate or
indeterminate progress bar, and in the former case, should indicate the relative position of the
current value relative to the maximum value.
- progress .
position -
For a determinate progress bar (one with known current and maximum values), returns the
result of dividing the current value by the maximum value.
For an indeterminate progress bar, returns −1.
If the progress bar is an indeterminate progress bar, then the position IDL attribute must return −1.
Otherwise, it must return the result of dividing the current
value by the maximum value.
If the progress bar is an indeterminate progress bar, then the value IDL attribute, on getting, must return 0.
Otherwise, it must return the current value. On
setting, the given value must be converted to the best representation of the number as a
floating-point number and then the value content
attribute must be set to that string.
Setting the value IDL attribute to itself
when the corresponding content attribute is absent would change the progress bar from an
indeterminate progress bar to a determinate progress bar with no progress.
The max IDL attribute must
reflect the content attribute of the same name, limited to numbers greater than
zero. The default value for max is 1.0.
The labels IDL attribute provides a list of the element's
labels.
The meter element
- Categories:
- Flow content.
- Phrasing content.
- Labelable element.
- Palpable content.
- Contexts in which this element can be used:
- Where phrasing content is expected.
- Content model:
- Phrasing content, but there must be no
meter element descendants. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
value — Current value of the elementmin — Lower bound of rangemax — Upper bound of rangelow — High limit of low rangehigh — Low limit of high rangeoptimum — Optimum value in gauge- Allowed ARIA role attribute values:
- None
- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- DOM interface:
-
interface HTMLMeterElement : HTMLElement {
attribute double value;
attribute double min;
attribute double max;
attribute double low;
attribute double high;
attribute double optimum;
readonly attribute NodeList labels;
};
The meter element represents a scalar measurement within a known
range, or a fractional value; for example disk usage, the relevance of a query result, or the
fraction of a voting population to have selected a particular candidate.
This is also known as a gauge.
The meter element should not be used to indicate progress (as in a
progress bar). For that role, HTML provides a separate progress element.
The meter element also does not represent a scalar value of arbitrary
range — for example, it would be wrong to use this to report a weight, or height, unless
there is a known maximum value.
There are six attributes that determine the semantics of the gauge represented by the
element.
The min attribute specifies the lower bound of
the range, and the max attribute specifies the
upper bound. The value attribute specifies the
value to have the gauge indicate as the "measured" value.
The other three attributes can be used to segment the gauge's range into "low", "medium", and
"high" parts, and to indicate which part of the gauge is the "optimum" part. The low attribute specifies the range that is considered to
be the "low" part, and the high attribute
specifies the range that is considered to be the "high" part. The optimum attribute gives the position that is
"optimum"; if that is higher than the "high" value then this indicates that the higher the value,
the better; if it's lower than the "low" mark then it indicates that lower values are better, and
naturally if it is in between then it indicates that neither high nor low values are good.
Authoring requirements: The value attribute must be specified. The value, min, low, high, max, and optimum attributes,
when present, must have values that are valid
floating-point numbers.
In addition, the attributes' values are further constrained:
Let value be the value attribute's
number.
If the min attribute is specified, then let minimum be that attribute's value; otherwise, let it be zero.
If the max attribute is specified, then let maximum be that attribute's value; otherwise, let it be 1.0.
The following inequalities must hold, as applicable:
- minimum ≤ value ≤ maximum
- minimum ≤
low ≤ maximum (if low is specified) - minimum ≤
high ≤ maximum (if high is specified) - minimum ≤
optimum ≤ maximum (if optimum is specified) low ≤ high (if
both low and high are
specified)
If no minimum or maximum is specified, then the range is assumed to be 0..1, and
the value thus has to be within that range.
Authors are encouraged to include a textual representation of the gauge's state in the
element's contents, for users of user agents that do not support the meter
element.
When used with microdata, the meter element's value attribute provides the element's machine-readable value.
The following examples show three gauges that would all be three-quarters full:
Storage space usage: <meter value=6 max=8>6 blocks used (out of 8 total)</meter>
Voter turnout: <meter value=0.75><img alt="75%" src="graph75.png"></meter>
Tickets sold: <meter min="0" max="100" value="75"></meter>
The following example is incorrect use of the element, because it doesn't give a range (and
since the default maximum is 1, both of the gauges would end up looking maxed out):
<p>The grapefruit pie had a radius of <meter value=12>12cm</meter>
and a height of <meter value=2>2cm</meter>.</p> <!-- BAD! -->
Instead, one would either not include the meter element, or use the meter element with a
defined range to give the dimensions in context compared to other pies:
<p>The grapefruit pie had a radius of 12cm and a height of
2cm.</p>
<dl>
<dt>Radius: <dd> <meter min=0 max=20 value=12>12cm</meter>
<dt>Height: <dd> <meter min=0 max=10 value=2>2cm</meter>
</dl>
There is no explicit way to specify units in the meter element, but the units may
be specified in the title attribute in free-form text.
The example above could be extended to mention the units:
<dl>
<dt>Radius: <dd> <meter min=0 max=20 value=12 title="centimeters">12cm</meter>
<dt>Height: <dd> <meter min=0 max=10 value=2 title="centimeters">2cm</meter>
</dl>
User agent requirements: User agents must parse the min, max, value, low, high, and optimum
attributes using the rules for parsing floating-point number values.
User agents must then use all these numbers to obtain values for six points on the gauge, as
follows. (The order in which these are evaluated is important, as some of the values refer to
earlier ones.)
- The minimum value
-
If the min attribute is specified and a value could be
parsed out of it, then the minimum value is that value. Otherwise, the minimum value is
zero.
- The maximum value
-
If the max attribute is specified and a value could be
parsed out of it, then the candidate maximum value is that value. Otherwise, the candidate
maximum value is 1.0.
If the candidate maximum value is greater than or equal to the minimum value, then the
maximum value is the candidate maximum value. Otherwise, the maximum value is the same as the
minimum value.
- The actual value
-
If the value attribute is specified and a value could
be parsed out of it, then that value is the candidate actual value. Otherwise, the candidate
actual value is zero.
If the candidate actual value is less than the minimum value, then the actual value is the
minimum value.
Otherwise, if the candidate actual value is greater than the maximum value, then the actual
value is the maximum value.
Otherwise, the actual value is the candidate actual value.
- The low boundary
-
If the low attribute is specified and a value could be
parsed out of it, then the candidate low boundary is that value. Otherwise, the candidate low
boundary is the same as the minimum value.
If the candidate low boundary is less than the minimum value, then the low boundary is the
minimum value.
Otherwise, if the candidate low boundary is greater than the maximum value, then the low
boundary is the maximum value.
Otherwise, the low boundary is the candidate low boundary.
- The high boundary
-
If the high attribute is specified and a value could be
parsed out of it, then the candidate high boundary is that value. Otherwise, the candidate high
boundary is the same as the maximum value.
If the candidate high boundary is less than the low boundary, then the high boundary is the
low boundary.
Otherwise, if the candidate high boundary is greater than the maximum value, then the high
boundary is the maximum value.
Otherwise, the high boundary is the candidate high boundary.
- The optimum point
-
If the optimum attribute is specified and a value
could be parsed out of it, then the candidate optimum point is that value. Otherwise, the
candidate optimum point is the midpoint between the minimum value and the maximum value.
If the candidate optimum point is less than the minimum value, then the optimum point is the
minimum value.
Otherwise, if the candidate optimum point is greater than the maximum value, then the optimum
point is the maximum value.
Otherwise, the optimum point is the candidate optimum point.
All of which will result in the following inequalities all being true:
- minimum value ≤ actual value ≤ maximum value
- minimum value ≤ low boundary ≤ high boundary ≤ maximum value
- minimum value ≤ optimum point ≤ maximum value
UA requirements for regions of the gauge: If the optimum point is equal to the
low boundary or the high boundary, or anywhere in between them, then the region between the low
and high boundaries of the gauge must be treated as the optimum region, and the low and high
parts, if any, must be treated as suboptimal. Otherwise, if the optimum point is less than the low
boundary, then the region between the minimum value and the low boundary must be treated as the
optimum region, the region from the low boundary up to the high boundary must be treated as a
suboptimal region, and the remaining region must be treated as an even less good region. Finally,
if the optimum point is higher than the high boundary, then the situation is reversed; the region
between the high boundary and the maximum value must be treated as the optimum region, the region
from the high boundary down to the low boundary must be treated as a suboptimal region, and the
remaining region must be treated as an even less good region.
UA requirements for showing the gauge: When representing a meter
element to the user, the UA should indicate the relative position of the actual value to the
minimum and maximum values, and the relationship between the actual value and the three regions of
the gauge.
The following markup:
<h3>Suggested groups</h3>
<menu type="toolbar">
<a href="?cmd=hsg" onclick="hideSuggestedGroups()">Hide suggested groups</a>
</menu>
<ul>
<li>
<p><a href="/group/comp.infosystems.www.authoring.stylesheets/view">comp.infosystems.www.authoring.stylesheets</a> -
<a href="/group/comp.infosystems.www.authoring.stylesheets/subscribe">join</a></p>
<p>Group description: <strong>Layout/presentation on the WWW.</strong></p>
<p><meter value="0.5">Moderate activity,</meter> Usenet, 618 subscribers</p>
</li>
<li>
<p><a href="/group/netscape.public.mozilla.xpinstall/view">netscape.public.mozilla.xpinstall</a> -
<a href="/group/netscape.public.mozilla.xpinstall/subscribe">join</a></p>
<p>Group description: <strong>Mozilla XPInstall discussion.</strong></p>
<p><meter value="0.25">Low activity,</meter> Usenet, 22 subscribers</p>
</li>
<li>
<p><a href="/group/mozilla.dev.general/view">mozilla.dev.general</a> -
<a href="/group/mozilla.dev.general/subscribe">join</a></p>
<p><meter value="0.25">Low activity,</meter> Usenet, 66 subscribers</p>
</li>
</ul>
Might be rendered as follows:
User agents may combine the value of the title attribute and the other attributes to provide context-sensitive
help or inline text detailing the actual values.
For example, the following snippet:
<meter min=0 max=60 value=23.2 title=seconds></meter>
...might cause the user agent to display a gauge with a tooltip
saying "Value: 23.2 out of 60." on one line and "seconds" on a
second line.
The value IDL attribute, on getting, must
return the actual value. On setting, the given value
must be converted to the best representation of the number as a floating-point number
and then the value content attribute must be set to that
string.
The min IDL attribute, on getting, must return
the minimum value. On setting, the given value must be
converted to the best representation of the number as a floating-point number and
then the min content attribute must be set to that string.
The max IDL attribute, on getting, must return
the maximum value. On setting, the given value must be
converted to the best representation of the number as a floating-point number and
then the max content attribute must be set to that string.
The low IDL attribute, on getting, must return
the low boundary. On setting, the given value must be
converted to the best representation of the number as a floating-point number and
then the low content attribute must be set to that string.
The high IDL attribute, on getting, must return
the high boundary. On setting, the given value must be
converted to the best representation of the number as a floating-point number and
then the high content attribute must be set to that
string.
The optimum IDL attribute, on getting, must
return the optimum value. On setting, the given value
must be converted to the best representation of the number as a floating-point number
and then the optimum content attribute must be set to that
string.
The labels IDL attribute provides a list of the element's
labels.
The following example shows how a gauge could fall back to localised or pretty-printed
text.
<p>Disk usage: <meter min=0 value=170261928 max=233257824>170 261 928 bytes used
out of 233 257 824 bytes available</meter></p>
The fieldset element
- Categories:
- Flow content.
- Sectioning root.
- Listed and reassociateable form-associated element.
- Palpable content.
- Contexts in which this element can be used:
- Where flow content is expected.
- Content model:
- Optionally a
legend element, followed by flow content. - Tag omission in text/html:
- Neither tag is omissible.
- Content attributes:
- Global attributes
disabled — Whether the form control is disabledform — Associates the control with a form elementname — Name of form control to use in the form.elements API - Allowed ARIA role attribute values:
group
(default - do not set)
or presentation.- Allowed ARIA State and Property Attributes:
- Global aria-* attributes
- Any
aria-* attributes
applicable to the allowed roles. - DOM interface:
-
interface HTMLFieldSetElement : HTMLElement {
attribute boolean disabled;
readonly attribute HTMLFormElement? form;
attribute DOMString name;
readonly attribute DOMString type;
readonly attribute HTMLFormControlsCollection elements;
readonly attribute boolean willValidate;
[SameObject] readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
boolean reportValidity();
void setCustomValidity(DOMString error);
};
The fieldset element represents a set of form controls optionally
grouped under a common name.
The name of the group is given by the first legend element that is a child of the
fieldset element, if any. The remainder of the descendants form the group.
The disabled attribute, when specified,
causes all the form control descendants of the fieldset element, excluding those that
are descendants of the fieldset element's first legend element child, if
any, to be disabled.
A fieldset element is a disabled
fieldset if it matches any of the following conditions:
- Its
disabled attribute is specified
- It is a descendant of another
fieldset element whose disabled attribute is specified, and is not a
descendant of that fieldset element's first legend element child, if
any.
The form attribute is used to explicitly associate the
fieldset element with its form owner. The name attribute represents the element's name.
- fieldset .
type -
Returns the string "fieldset".
- fieldset .
elements -
Returns an HTMLFormControlsCollection of the form controls in the element.
The disabled IDL attribute must
reflect the content attribute of the same name.
The type IDL attribute must return the string
"fieldset".
The elements IDL attribute must return an
HTMLFormControlsCollection rooted at the fieldset element, whose filter
matches listed elements.
The willValidate, validity, and validationMessage attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the
constraint validation API. The form and name IDL attributes are part of the element's forms API.
This example shows a fieldset element being used to group a set of related
controls:
<fieldset>
<legend>Display</legend>
<p><label><input type=radio name=c value=0 checked> Black on White</label>
<p><label><input type=radio name=c value=1> White on Black</label>
<p><label><input type=checkbox name=g> Use grayscale</label>
<p><label>Enhance contrast <input type=range name=e list=contrast min=0 max=100 value=0 step=1></label>
<datalist id=contrast>
<option label=Normal value=0>
<option label=Maximum value=100>
</datalist>
</fieldset>
The following snippet shows a fieldset with a checkbox in the legend that controls whether or
not the fieldset is enabled. The contents of the fieldset consist of two required text fields and
an optional year/month control.
<fieldset name="clubfields" disabled>
<legend> <label>
<input type=checkbox name=club onchange="form.clubfields.disabled = !checked">
Use Club Card
</label> </legend>
<p><label>Name on card: <input name=clubname required></label></p>
<p><label>Card number: <input name=clubnum required pattern="[-0-9]+"></label></p>
<p><label>Expiry date: <input name=clubexp type=month></label></p>
</fieldset>
You can also nest fieldset elements. Here is an example expanding on the previous
one that does so:
<fieldset name="clubfields" disabled>
<legend> <label>
<input type=checkbox name=club onchange="form.clubfields.disabled = !checked">
Use Club Card
</label> </legend>
<p><label>Name on card: <input name=clubname required></label></p>
<fieldset name="numfields">
<legend> <label>
<input type=radio checked name=clubtype onchange="form.numfields.disabled = !checked">
My card has numbers on it
</label> </legend>
<p><label>Card number: <input name=clubnum required pattern="[-0-9]+"></label></p>
</fieldset>
<fieldset name="letfields" disabled>
<legend> <label>
<input type=radio name=clubtype onchange="form.letfields.disabled = !checked">
My card has letters on it
</label> </legend>
<p><label>Card code: <input name=clublet required pattern="[A-Za-z]+"></label></p>
</fieldset>
</fieldset>
In this example, if the outer "Use Club Card" checkbox is not checked, everything inside the
outer fieldset, including the two radio buttons in the legends of the two nested
fieldsets, will be disabled. However, if the checkbox is checked, then the radio
buttons will both be enabled and will let you select which of the two inner
fieldsets is to be enabled.
Form control infrastructure
A form control's value
Most form controls have a value and a checkedness. (The latter is only used by input
elements.) These are used to describe how the user interacts with the control.
A control's value is its internal state. As such, it
might not match the user's current input.
For instance, if a user enters the word "three" into a numeric field that expects digits, the user's input would
be the string "three" but the control's value would remain
unchanged.
To define the behaviour of constraint validation in the face of the input
element's multiple attribute, input elements
can also have separately defined values.
The select element does not have a value;
the selectedness of its option
elements is what is used instead.
Mutability
A form control can be designated as mutable.
This determines (by means of definitions and requirements in this specification
that rely on whether an element is so designated) whether or not the user can modify the value or checkedness of a
form control, or whether or not a control can be automatically prefilled.
Association of controls and forms
A form-associated element can have a relationship with a form
element, which is called the element's form owner. If a form-associated
element is not associated with a form element, its form owner is
said to be null.
A form-associated element is, by default, associated with its nearest ancestor form element (as described
below), but, if it is reassociateable, may have a
form attribute specified to override this.
This feature allows authors to work around the lack of support for nested
form elements.
If a reassociateable form-associated
element has a form attribute specified, then that
attribute's value must be the ID of a form element
in the element's owner Document.
The rules in this section are complicated by the fact that although conforming
documents will never contain nested form elements, it is quite possible (e.g. using a
script that performs DOM manipulation) to generate documents that have such nested elements. They
are also complicated by rules in the HTML parser that, for historical reasons, can result in a
form-associated element being associated with a form element that is not
its ancestor.
When a form-associated element is created, its form owner must be
initialised to null (no owner).
When a form-associated element is to be associated with a form, its form owner must
be set to that form.
When a form-associated element or one of its ancestors is inserted into a Document, then the user agent must
reset the form owner of that form-associated element. The HTML parser overrides this requirement when inserting form
controls.
When an element changes its parent node resulting in a form-associated element and
its form owner (if any) no longer being in the same home subtree, then
the user agent must reset the form owner of that form-associated
element.
When a reassociateable form-associated
element's form attribute is set, changed, or removed,
then the user agent must reset the form owner of that element.
When a reassociateable form-associated
element has a form attribute and the ID of any of the elements in the Document changes, then
the user agent must reset the form owner of that form-associated
element.
When a reassociateable form-associated
element has a form attribute and an element with an
ID is inserted
into or removed from the
Document, then the user agent must reset the form owner of that
form-associated element.
When the user agent is to reset the form owner of a form-associated
element, it must run the following steps:
If the element's form owner is not null, and either the element is not reassociateable or its form content attribute is not present, and the element's form
owner is its nearest form element ancestor after the change to the ancestor
chain, then do nothing, and abort these steps.
Let the element's form owner be null.
-
If the element is reassociateable, has a form content attribute, and is itself in a Document, then run these substeps:
If the first element in the Document to
have an ID that is case-sensitively equal to the element's form content attribute's value is a form element,
then associate the form-associated
element with that form element.
Abort the "reset the form owner" steps.
Otherwise, if the form-associated element in question has an ancestor
form element, then associate the
form-associated element with the nearest such ancestor form
element.
Otherwise, the element is left unassociated.
In the following non-conforming snippet:
...
<form id="a">
<div id="b"></div>
</form>
<script>
document.getElementById('b').innerHTML =
'<table><tr><td><form id="c"><input id="d"></table>' +
'<input id="e">';
</script>
...
The form owner of "d" would be the inner nested form "c", while the form
owner of "e" would be the outer form "a".
This happens as follows: First, the "e" node gets associated with "c" in the HTML
parser. Then, the innerHTML algorithm moves the nodes
from the temporary document to the "b" element. At this point, the nodes see their ancestor chain
change, and thus all the "magic" associations done by the parser are reset to normal ancestor
associations.
This example is a non-conforming document, though, as it is a violation of the content models
to nest form elements.
- element .
form -
Returns the element's form owner.
Returns null if there isn't one.
Reassociateable form-associated elements have a form
IDL attribute, which, on getting, must return the element's form owner, or null if
there isn't one.
Attributes common to form controls
Naming form controls: the name attribute
The name content attribute gives the name of the
form control, as used in form submission and in the form element's elements object. If the attribute is specified, its value must
not be the empty string.
Any non-empty value for name is allowed, but the names
"_charset_" and "isindex" are special:
isindex-
This value, if used as the name of a Text control
that is the first control in a form that is submitted using the application/x-www-form-urlencoded mechanism, causes
the submission to only include the value of this control, with no name.
_charset_-
This value, if used as the name of a Hidden
control with no value attribute, is automatically given a
value during submission consisting of the submission character encoding.
The name IDL attribute must reflect
the name content attribute.
Submitting element directionality: the dirname attribute
The dirname attribute on a form control element
enables the submission of the directionality of the element, and gives the name of
the field that contains this value during form submission. If such an attribute is
specified, its value must not be the empty string.
In this example, a form contains a text field and a submission button:
<form action="addcomment.cgi" method=post>
<p><label>Comment: <input type=text name="comment" dirname="comment.dir" required></label></p>
<p><button name="mode" type=submit value="add">Post Comment</button></p>
</form>
When the user submits the form, the user agent includes three fields, one called "comment",
one called "comment.dir", and one called "mode"; so if the user types "Hello", the submission
body might be something like:
comment=Hello&comment.dir=ltr&mode=add
If the user manually switches to a right-to-left writing direction and enters "مرحبا", the submission body might be
something like:
comment=%D9%85%D8%B1%D8%AD%D8%A8%D8%A7&comment.dir=rtl&mode=add
Limiting user input length: the maxlength attribute
A form control maxlength attribute,
controlled by a dirty value flag, declares a limit on the number of characters
a user can input.
If an element has its form control maxlength attribute specified, the attribute's value must be a valid
non-negative integer. If the attribute is specified and applying the rules for
parsing non-negative integers to its value results in a number, then that number is the
element's maximum allowed value length. If the attribute is omitted or parsing its
value results in an error, then there is no maximum allowed value length.
Constraint validation: If an element has a maximum allowed value
length, its dirty value flag is true, its value was last changed by a user edit (as opposed to a change made
by a script), and the code-unit length of the element's value is greater than the element's maximum allowed value
length, then the element is suffering from being too long.
User agents may prevent the user from causing the element's value to be set to a value whose code-unit length is
greater than the element's maximum allowed value length.
In the case of textarea elements, this is the value, not the raw
value, so the textarea wrapping transformation is applied before the
maximum allowed value length is checked.
Setting minimum input length requirements: the minlength attribute
A form control minlength attribute,
controlled by a dirty value flag, declares a lower bound on the number of
characters a user can input.
The minlength attribute does not imply the
required attribute. If the form control has no required attribute, then the value can still be omitted; the
minlength attribute only kicks in once the user has entered
a value at all. If the empty string is not allowed, then the required
attribute also needs to be set.
If an element has its form control minlength attribute specified, the attribute's value must be a valid
non-negative integer. If the attribute is specified and applying the rules for
parsing non-negative integers to its value results in a number, then that number is the
element's minimum allowed value length. If the attribute is omitted or parsing its
value results in an error, then there is no minimum allowed value length.
If an element has both a maximum allowed value length and a minimum allowed
value length, the minimum allowed value length must be smaller than or equal
to the maximum allowed value length.
Constraint validation: If an element has a minimum allowed value
length, its value is not the empty string, and the
code-unit length of the element's value is less
than the element's minimum allowed value length, then the element is suffering
from being too short.
In this example, there are four text fields. The first is required, and has to be at least 5
characters long. The other three are optional, but if the user fills one in, the user has to
enter at least 10 characters.
<form action="/events/menu.cgi" method="post">
<p><label>Name of Event: <input required minlength=5 maxlength=50 name=event></label></p>
<p><label>Describe what you would like for breakfast, if anything:
<textarea name="breakfast" minlength="10"></textarea></label></p>
<p><label>Describe what you would like for lunch, if anything:
<textarea name="lunch" minlength="10"></textarea></label></p>
<p><label>Describe what you would like for dinner, if anything:
<textarea name="dinner" minlength="10"></textarea></label></p>
<p><input type=submit value="Submit Request"></p>
</form>
Form submission
Attributes for form submission can be specified both on form elements
and on submit buttons (elements that represent buttons
that submit forms, e.g. an input element whose type attribute is in the Submit Button state).
The attributes for form submission that may be specified on form
elements are action, enctype, method, novalidate, and target.
The corresponding attributes for form submission that may be specified on submit buttons are formaction, formenctype, formmethod, formnovalidate, and formtarget. When omitted, they default to the values given on
the corresponding attributes on the form element.
The action and formaction content attributes, if specified, must
have a value that is a valid non-empty URL potentially surrounded by spaces.
The action of an element is the value of the element's
formaction attribute, if the element is a submit button and has such an attribute, or the value of its
form owner's action attribute, if it has
one, or else the empty string.
The method and formmethod content attributes are enumerated attributes with the following keywords and
states:
- The keyword
get, mapping to the
state GET, indicating the HTTP GET method. - The keyword
post, mapping to the
state POST, indicating the HTTP POST method. - The keyword
dialog, mapping to
the state dialog, indicating that submitting the
form is intended to close the dialog box in which the form finds
itself, if any, and otherwise not submit.
The invalid value default for these attributes is the GET state. The missing value default for the method attribute is also the GET state. (There is no missing value default for the
formmethod attribute.)
The method of an element is one of those states. If the
element is a submit button and has a formmethod attribute, then the element's method is that attribute's state; otherwise, it is the form
owner's method attribute's state.
Here the method attribute is used to explicitly specify
the default value, "get", so that the search
query is submitted in the URL:
<form method="get" action="/search.cgi">
<p><label>Search terms: <input type=search name=q></label></p>
<p><input type=submit></p>
</form>
On the other hand, here the method attribute is used to
specify the value "post", so that the user's
message is submitted in the HTTP request's body:
<form method="post" action="/post-message.cgi">
<p><label>Message: <input type=text name=m></label></p>
<p><input type=submit value="Submit message"></p>
</form>
In this example, a form is used with a dialog. The method attribute's "dialog" keyword is used to have the dialog
automatically close when the form is submitted.
<dialog id="ship">
<form method=dialog>
<p>A ship has arrived in the harbour.</p>
<button type=submit value="board">Board the ship</button>
<button type=submit value="call">Call to the captain</button>
</form>
</dialog>
<script>
var ship = document.getElementById('ship');
ship.showModal();
ship.onclose = function (event) {
if (ship.returnValue == 'board') {
// ...
} else {
// ...
}
};
</script>
The enctype and formenctype content attributes are enumerated attributes with the following keywords and
states:
- The "
application/x-www-form-urlencoded" keyword and corresponding state. - The "
multipart/form-data" keyword and corresponding state. - The "
text/plain" keyword and corresponding state.
The invalid value default for these attributes is the application/x-www-form-urlencoded state. The missing value default for the enctype attribute is also the application/x-www-form-urlencoded state. (There is no
missing value default for the formenctype
attribute.)
The enctype of an element is one of those three states.
If the element is a submit button and has a formenctype attribute, then the element's enctype is that attribute's state; otherwise, it is the
form owner's enctype attribute's state.
The target and formtarget content attributes, if specified, must
have values that are valid browsing context
names or keywords.
The target of an element is the value of the element's
formtarget attribute, if the element is a submit button and has such an attribute; or the value of its
form owner's target attribute, if it has
such an attribute; or, if the Document contains a base element with a
target attribute, then the value of the target attribute of the first such base element; or,
if there is no such element, the empty string.
The novalidate and formnovalidate content attributes are boolean attributes. If present, they indicate that the form is
not to be validated during submission.
The no-validate state of an element is true if the
element is a submit button and the element's formnovalidate attribute is present, or if the element's
form owner's novalidate attribute is present,
and false otherwise.
This attribute is useful to include "save" buttons on forms that have validation constraints,
to allow users to save their progress even though they haven't fully entered the data in the
form. The following example shows a simple form that has two required fields. There are three
buttons: one to submit the form, which requires both fields to be filled in; one to save the form
so that the user can come back and fill it in later; and one to cancel the form altogether.
<form action="editor.cgi" method="post">
<p><label>Name: <input required name=fn></label></p>
<p><label>Essay: <textarea required name=essay></textarea></label></p>
<p><input type=submit name=submit value="Submit essay"></p>
<p><input type=submit formnovalidate name=save value="Save essay"></p>
<p><input type=submit formnovalidate name=cancel value="Cancel"></p>
</form>
The action IDL attribute must
reflect the content attribute of the same name, except that on getting, when the
content attribute is missing or its value is the empty string, the document's address
must be returned instead. The target IDL attribute
must reflect the content attribute of the same name. The method and enctype IDL attributes must reflect the
respective content attributes of the same name, limited to only known values. The
encoding IDL attribute must reflect
the enctype content attribute, limited to only known
values. The noValidate IDL attribute must
reflect the novalidate content attribute. The
formAction IDL attribute must
reflect the formaction content attribute,
except that on getting, when the content attribute is missing or its value is the empty string,
the document's address must be returned instead. The formEnctype IDL attribute must reflect
the formenctype content attribute, limited to only
known values. The formMethod IDL
attribute must reflect the formmethod content
attribute, limited to only known values. The formNoValidate IDL attribute must
reflect the formnovalidate content
attribute. The formTarget IDL attribute must
reflect the formtarget content attribute.
Autofocusing a form control: the autofocus attribute
The autofocus content attribute allows the
author to indicate that a control is to be focused as soon as the page is loaded or as soon as the
dialog within which it finds itself is shown, allowing the user to just start typing
without having to manually focus the main control.
The autofocus attribute is a boolean
attribute.
An element's nearest ancestor autofocus scoping root element is the element itself
if the element is a dialog element, or else is the element's nearest ancestor
dialog element, if any, or else is the element's root element.
There must not be two elements with the same nearest ancestor autofocus scoping root
element that both have the autofocus attribute
specified.
When an element with the autofocus attribute specified
is inserted into a document, user agents
should run the following steps:
Let target be the element's node document.
If target has no browsing context, abort these
steps.
If target's browsing context has no top-level
browsing context (e.g. it is a nested browsing context with no parent
browsing context), abort these steps.
If target's active sandboxing flag set has the
sandboxed automatic features browsing context flag, abort these steps.
If target's origin is not the same as the origin of the node document of the currently
focused element in target's top-level browsing context, abort
these steps.
If target's origin is not the same as the origin of the active document of target's top-level browsing context, abort these steps.
If the user agent has already reached the last step of this list of steps in response to
an element being inserted into a
Document whose top-level browsing context's active
document is the same as target's top-level browsing
context's active document, abort these steps.
If the user has indicated (for example, by starting to type in a form control) that he
does not wish focus to be changed, then optionally abort these steps.
Queue a task that runs the focusing steps for the element. User
agents may also change the scrolling position of the document, or perform some other action that
brings the element to the user's attention. The task source for this task is the
user interaction task source.
This handles the automatic focusing during document load. The show() and showModal()
methods of dialog elements also processes the autofocus attribute.
Focusing the control does not imply that the user agent must focus the browser
window if it has lost focus.
The autofocus IDL attribute must
reflect the content attribute of the same name.
In the following snippet, the text control would be focused when
the document was loaded.
<input maxlength="256" name="q" value="" autofocus>
<input type="submit" value="Search">
Input modalities: the inputmode attribute
The inputmode content attribute is an
enumerated attribute that specifies what kind of input mechanism would be most
helpful for users entering content into the form control.
User agents must recognise all the keywords and corresponding states given below, but need not
support all of the corresponding states. If a keyword's state is not supported, the user agent
must act as if the keyword instead mapped to the given state's fallback state, as defined below.
This fallback behaviour is transitive.
For example, if a user agent with a QWERTY keyboard layout does not support text
prediction and automatic capitalization, then it could treat the latin-prose keyword in the same way as the
verbatim keyword, following the chain
Latin Prose → Latin Text → Latin Verbatim.
The possible keywords and states for the attributes are listed in the following table. The
keywords are listed in the first column. Each maps to the state given in the cell in the second
column of that keyword's row, and that state has the fallback state given in the cell in the third
column of that row.
| Keyword
| State
| Fallback state
| Description
|
|---|
verbatim
| Latin Verbatim
| Default
| Alphanumeric Latin-script input of non-prose content, e.g. usernames, passwords, product codes.
|
latin
| Latin Text
| Latin Verbatim
| Latin-script input in the user's preferred language(s), with some typing aids enabled
(e.g. text prediction). Intended for human-to-computer communications, e.g. free-form text
search fields.
|
latin-name
| Latin Name
| Latin Text
| Latin-script input in the user's preferred language(s), with typing aids intended for
entering human names enabled (e.g. text prediction from the user's contact list and automatic
capitalisation at every word). Intended for situations such as customer name fields.
|
latin-prose
| Latin Prose
| Latin Text
| Latin-script input in the user's preferred language(s), with aggressive typing aids
intended for human-to-human communications enabled (e.g. text prediction and automatic
capitalisation at the start of sentences). Intended for situations such as e-mails and instant
messaging.
|
full-width-latin
| Full-width Latin
| Latin Prose
| Latin-script input in the user's secondary language(s), using full-width characters, with
aggressive typing aids intended for human-to-human communications enabled (e.g. text prediction
and automatic capitalisation at the start of sentences). Intended for latin text embedded
inside CJK text.
|
kana
| Kana
| Default
| Kana or romaji input, typically hiragana input, using full-width characters, with support
for converting to kanji. Intended for Japanese text input.
|
kana-name
| Kana Name
| Kana
| Kana or romaji input, typically hiragana input, using full-width characters, with support
for converting to kanji, and with typing aids intended for entering human names enabled (e.g.
text prediction from the user's contact list). Intended for situations such as customer name
fields.
|
katakana
| Katakana
| Kana
| Katakana input, using full-width characters, with support for converting to kanji.
Intended for Japanese text input.
|
numeric
| Numeric
| Default
| Numeric input, including keys for the digits 0 to 9, the user's preferred thousands
separator character, and the character for indicating negative numbers. Intended for numeric
codes, e.g. credit card numbers. (For numbers, prefer "<input type=number>".)
|
tel
| Telephone
| Numeric
| Telephone number input, including keys for the digits 0 to 9, the "#" character, and the
"*" character. In some locales, this can also include alphabetic mnemonic labels (e.g. in the
US, the key labeled "2" is historically also labeled with the letters A, B, and C). Rarely necessary; use "<input
type=tel>" instead.
|
email
| E-mail
| Default
| Text input in the user's locale, with keys for aiding in the input of e-mail addresses,
such as that for the "@" character and the "." character. Rarely
necessary; use "<input type=email>" instead.
|
url
| URL
| Default
| Text input in the user's locale, with keys for aiding in the input of Web addresses, such
as that for the "/" and "." characters and for quick input of strings commonly found in domain
names such as "www." or ".co.uk". Rarely necessary; use "<input type=url>" instead.
|
The last three keywords listed above are only provided for completeness,
and are rarely necessary, as dedicated input controls exist for their usual use cases (as
described in the table above).
User agents must all support the Default input mode state, which corresponds to the
user agent's default input modality. This specification does not define how the
user agent's default modality is to operate. The missing value default is the default input mode state.
User agents should use the input modality corresponding to the state of the inputmode attribute when exposing a user interface for editing
the value of a form control to which the attribute applies. An input modality corresponding to a state is one
designed to fit the description of the state in the table above. This value can change
dynamically; user agents should update their interface as the attribute changes state, unless that
would go against the user's wishes.
Autofill
Autofilling form controls: the autocomplete attribute
User agents sometimes have features for helping users fill forms in, for example prefilling the
user's address based on earlier user input. The autocomplete content attribute can be used to hint
to the user agent how to, or indeed whether to, provide such a feature.
There are two ways this attribute is used. When wearing the autofill expectation
mantle, the autocomplete attribute describes what
input is expected from users. When wearing the autofill anchor mantle, the autocomplete attribute describes the meaning of the given
value.
On an input element whose type attribute is
in the Hidden state, the autocomplete attribute wears the autofill anchor
mantle. In all other cases, it wears the autofill expectation mantle.
When wearing the autofill expectation mantle, the autocomplete attribute, if specified, must have a value that
is an ordered set of space-separated tokens consisting of either a single token that
is an ASCII case-insensitive match for the string "off", or a single token that is an ASCII
case-insensitive match for the string "on",
or autofill detail tokens.
When wearing the autofill anchor
mantle, the autocomplete attribute, if specified, must have a value that is an ordered set of
space-separated tokens consisting of just autofill detail tokens (i.e. the
"on" and "off" keywords are not allowed).
Autofill detail tokens are the following, in the order given below:
-
Optionally, a token whose first eight characters are an ASCII case-insensitive
match for the string "section-",
meaning that the field belongs to the named group.
For example, if there are two shipping addresses in the form, then they could be marked up
as:
<fieldset>
<legend>Ship the blue gift to...</legend>
<p> <label> Address: <input name=ba autocomplete="section-blue shipping street-address"> </label>
<p> <label> City: <input name=bc autocomplete="section-blue shipping address-level1"> </label>
<p> <label> Postal Code: <input name=bp autocomplete="section-blue shipping postal-code"> </label>
</fieldset>
<fieldset>
<legend>Ship the red gift to...</legend>
<p> <label> Address: <input name=ra autocomplete="section-red shipping street-address"> </label>
<p> <label> City: <input name=rc autocomplete="section-red shipping address-level1"> </label>
<p> <label> Postal Code: <input name=rp autocomplete="section-red shipping postal-code"> </label>
</fieldset>
-
Optionally, a token that is an ASCII case-insensitive match for one of the
following strings:
- "
shipping", meaning the field
is part of the shipping address or contact information
- "
billing", meaning the field
is part of the billing address or contact information
-
Either of the following two options:
-
A token that is an ASCII case-insensitive match for one of the following
autofill field names, excluding those that are inappropriate for the
control:
(See the table below for descriptions of these values.)
-
The following, in the given order:
-
Optionally, a token that is an ASCII case-insensitive match for one of the
following strings:
- "
home", meaning the field is
for contacting someone at their residence
- "
work", meaning the field is
for contacting someone at their workplace
- "
mobile", meaning the field is for contacting someone regardless of location
- "
fax", meaning the field
describes a fax machine's contact details
- "", meaning the field
describes a pager's or beeper's contact details
-
A token that is an ASCII case-insensitive match for one of the following
autofill field names, excluding those that are inappropriate for the
control:
(See the table below for descriptions of these values.)
As noted earlier, the meaning of the attribute and its keywords depends on the mantle that the
attribute is wearing.
- When wearing the autofill expectation mantle...
-
The "off" keyword indicates either
that the control's input data is particularly sensitive (for example the activation code for a
nuclear weapon); or that it is a value that will never be reused (for example a one-time-key for a
bank login) and the user will therefore have to explicitly enter the data each time, instead of
being able to rely on the UA to prefill the value for him; or that the document provides its own
autocomplete mechanism and does not want the user agent to provide autocompletion values.
The "on" keyword indicates that the
user agent is allowed to provide the user with autocompletion values, but does not provide any
further information about what kind of data the user might be expected to enter. User agents would
have to use heuristics to decide what autocompletion values to suggest.
The autofill field listed above indicate that the user agent is allowed to
provide the user with autocompletion values, and specifies what kind of value is expected. The
meaning of each such keyword is described in the table below.
If the autocomplete attribute is omitted, the default
value corresponding to the state of the element's form owner's autocomplete attribute is used instead (either "on" or "off"). If there is no form owner, then the
value "on" is used.
- When wearing the autofill anchor mantle...
-
The autofill field listed above indicate that the value of the particular kind
of value specified is that value provided for this element. The meaning of each such keyword is
described in the table below.
In this example the page has explicitly specified the currency and amount of the
transaction. The form requests a credit card and other billing details. The user agent could
use this information to suggest a credit card that it knows has sufficient balance and that
supports the relevant currency.
<form method=post action="step2.cgi">
<input type=hidden autocomplete=transaction-currency value="CHF">
<input type=hidden autocomplete=transaction-amount value="15.00">
<p><label>Credit card number: <input type=text inputmode=numeric autocomplete=cc-number></label>
<p><label>Expiry Date: <input type=month autocomplete=cc-exp></label>
<p><input type=submit value="Continue...">
</form>
The autofill field keywords relate to each other as described in the table below. Each field name
listed on a row of this table corresponds to the meaning given in the cell for that row in the
column labeled "Meaning". Some fields correspond to subparts of other fields; for example, a
credit card expiry date can be expressed as one field giving both the month and year of expiry
("cc-exp"), or as two fields, one giving the
month ("cc-exp-month") and one the year
("cc-exp-year"). In such cases, the names of
the broader fields cover multiple rows, in which the narrower fields are defined.
Generally, authors are encouraged to use the broader fields rather than the
narrower fields, as the narrower fields tend to expose Western biases. For example, while it is
common in some Western cultures to have a given name and a family name, in that order (and thus
often referred to as a first name and a surname), many cultures put the family name
first and the given name second, and many others simply have one name (a mononym). Having a
single field is therefore more flexible.
Some fields are only appropriate for certain form controls. An autofill field name
is inappropriate for a control if the control
does not belong to the group listed for that autofill field in the fifth column of
the first row describing that autofill field in the table below. What controls fall
into each group is described below the table.
| Field name
| Meaning
| Canonical Format
| Canonical Format Example
| Control group
|
|---|
"name"
| Full name
| Free-form text, no newlines
| Sir Timothy John Berners-Lee, OM, KBE, FRS, FREng, FRSA
| Text
|
|
| "honorific-prefix"
| Prefix or title (e.g. "Mr.", "Ms.", "Dr.", "Mlle")
| Free-form text, no newlines
| Sir
| Text
|
"given-name"
| Given name (in some Western cultures, also known as the first name)
| Free-form text, no newlines
| Timothy
| Text
|
"additional-name"
| Additional names (in some Western cultures, also known as middle names, forenames other than the first name)
| Free-form text, no newlines
| John
| Text
|
"family-name"
| Family name (in some Western cultures, also known as the last name or surname)
| Free-form text, no newlines
| Berners-Lee
| Text
|
"honorific-suffix"
| Suffix (e.g. "Jr.", "B.Sc.", "MBASW", "II")
| Free-form text, no newlines
| OM, KBE, FRS, FREng, FRSA
| Text
|
"nickname"
| Nickname, screen name, handle: a typically short name used instead of the full name
| Free-form text, no newlines
| Tim
| Text
|
"organization-title"
| Job title (e.g. "Software Engineer", "Senior Vice President", "Deputy Managing Director")
| Free-form text, no newlines
| Professor
| Text
|
"username"
| A username
| Free-form text, no newlines
| timbl
| Text
|
"new-password"
| A new password (e.g. when creating an account or changing a password)
| Free-form text, no newlines
| GUMFXbadyrS3
| Password
|
"current-password"
| The current password for the account identified by the username field (e.g. when logging in)
| Free-form text, no newlines
| qwerty
| Password
|
"organization"
| Company name corresponding to the person, address, or contact information in the other fields associated with this field
| Free-form text, no newlines
| World Wide Web Consortium
| Text
|
"street-address"
| Street address (multiple lines, newlines preserved)
| Free-form text
| 32 Vassar Street
MIT Room 32-G524
| Multiline
|
|
| "address-line1"
| Street address (one line per field)
| Free-form text, no newlines
| 32 Vassar Street
| Text
|
"address-line2"
| Free-form text, no newlines
| MIT Room 32-G524
| Text
|
"address-line3"
| Free-form text, no newlines
|
| Text
|
"address-level4"
| The most fine-grained administrative level, in
addresses with four administrative levels
| Free-form text, no newlines
|
| Text
|
"address-level3"
| The third administrative level, in addresses with
three or more administrative levels
| Free-form text, no newlines
|
| Text
|
"address-level2"
| The second administrative level, in addresses with
two or more administrative levels; in the countries with two administrative levels, this would
typically be the city, town, village, or other locality within which the relevant street
address is found
| Free-form text, no newlines
| Cambridge
| Text
|
"address-level1"
| The broadest administrative level in the address,
i.e. the province within which the locality is found; for example, in the US, this would be the
state; in Switzerland it would be the canton; in the UK, the post town
| Free-form text, no newlines
| MA
| Text
|
"country"
| Country code
| Valid ISO 3166-1-alpha-2 country code [[!ISO3166]]
| US
| Text
|
"country-name"
| Country name
| Free-form text, no newlines; derived from country in some cases
| US
| Text
|
"postal-code"
| Postal code, post code, ZIP code, CEDEX code (if CEDEX, append "CEDEX", and the arrondissement, if relevant, to the address-level2 field)
| Free-form text, no newlines
| 02139
| Text
|
"cc-name"
| Full name as given on the payment instrument
| Free-form text, no newlines
| Tim Berners-Lee
| Text
|
|
| "cc-given-name"
| Given name as given on the payment instrument (in some Western cultures, also known as the first name)
| Free-form text, no newlines
| Tim
| Text
|
"cc-additional-name"
| Additional names given on the payment instrument (in some Western cultures, also known as middle names, forenames other than the first name)
| Free-form text, no newlines
|
| Text
|
"cc-family-name"
| Family name given on the payment instrument (in some Western cultures, also known as the last name or surname)
| Free-form text, no newlines
| Berners-Lee
| Text
|
"cc-number"
| Code identifying the payment instrument (e.g. the credit card number)
| ASCII digits
| 4114360123456785
| Text
|
"cc-exp"
| Expiration date of the payment instrument
| Valid month string
| 2014-12
| Month
|
|
| "cc-exp-month"
| Month component of the expiration date of the payment instrument
| Valid integer in the range 1..12
| 12
| Numeric
|
"cc-exp-year"
| Year component of the expiration date of the payment instrument
| Valid integer greater than zero
| 2014
| Numeric
|
"cc-csc"
| Security code for the payment instrument (also known as the card security code (CSC), card validation code (CVC), card verification value (CVV), signature panel code (SPC), credit card ID (CCID), etc)
| ASCII digits
| 419
| Text
|
"cc-type"
| Type of payment instrument
| Free-form text, no newlines
| Visa
| Text
|
"transaction-currency"
| The currency that the user would prefer the transaction to use
| ISO 4217 currency code [[!ISO4217]]
| GBP
| Text
|
"transaction-amount"
| The amount that the user would like for the transaction (e.g. when entering a bid or sale price)
| Valid floating-point number
| 401.00
| Numeric
|
"language"
| Preferred language
| Valid BCP 47 language tag [[!BCP47]]
| en
| Text
|
"bday"
| Birthday
| Valid date string
| 1955-06-08
| Date
|
|
| "bday-day"
| Day component of birthday
| Valid integer in the range 1..31
| 8
| Numeric
|
"bday-month"
| Month component of birthday
| Valid integer in the range 1..12
| 6
| Numeric
|
"bday-year"
| Year component of birthday
| Valid integer greater than zero
| 1955
| Numeric
|
"sex"
| Gender identity (e.g. Female, Fa'afafine)
| Free-form text, no newlines
| Male
| Text
|
"url"
| Home page or other Web page corresponding to the company, person, address, or contact information in the other fields associated with this field
| Valid URL
| http://www.w3.org/People/Berners-Lee/
| URL
|
"photo"
| Photograph, icon, or other image corresponding to the company, person, address, or contact information in the other fields associated with this field
| Valid URL
| http://www.w3.org/Press/Stock/Berners-Lee/2001-europaeum-eighth.jpg
| URL
|
"tel"
| Full telephone number, including country code
| ASCII digits and U+0020 SPACE characters, prefixed by a U+002B PLUS SIGN character (+)
| +1 617 253 5702
| Tel
|
|
| "tel-country-code"
| Country code component of the telephone number
| ASCII digits prefixed by a U+002B PLUS SIGN character (+)
| +1
| Text
|
"tel-national"
| Telephone number without the county code component, with a country-internal prefix applied if applicable
| ASCII digits and U+0020 SPACE characters
| 617 253 5702
| Text
|
|
| "tel-area-code"
| Area code component of the telephone number, with a country-internal prefix applied if applicable
| ASCII digits
| 617
| Text
|
"tel-local"
| Telephone number without the country code and area code components
| ASCII digits
| 2535702
| Text
|
|
| "tel-local-prefix"
| First part of the component of the telephone number that follows the area code, when that component is split into two components
| ASCII digits
| 253
| Text
|
"tel-local-suffix"
| Second part of the component of the telephone number that follows the area code, when that component is split into two components
| ASCII digits
| 5702
| Text
|
"tel-extension"
| Telephone number internal extension code
| ASCII digits
| 1000
| Text
|
"email"
| E-mail address
| Valid e-mail address
| timbl@w3.org
| E-mail
|
"impp"
| URL representing an instant messaging protocol endpoint (for example, "aim:goim?screenname=example" or "xmpp:fred@example.net")
| Valid URL
| irc://example.org/timbl,isuser
| URL
|
The groups correspond to controls as follows:
- Text
input elements with a type attribute in the Hidden state
input elements with a type attribute in the Text state
input elements with a type attribute in the Search state
textarea elements
select elements
- Multiline
input elements with a type attribute in the Hidden state
textarea elements
select elements
- Password
input elements with a type attribute in the Hidden state
input elements with a type attribute in the Text state
input elements with a type attribute in the Search state
input elements with a type attribute in the Password state
textarea elements
select elements
- URL
input elements with a type attribute in the Hidden state
input elements with a type attribute in the Text state
input elements with a type attribute in the Search state
input elements with a type attribute in the URL state
textarea elements
select elements
- E-mail
input elements with a type attribute in the Hidden state
input elements with a type attribute in the Text state
input elements with a type attribute in the Search state
input elements with a type attribute in the E-mail state
textarea elements
select elements
- Tel
input elements with a type attribute in the Hidden state
input elements with a type attribute in the Text state
input elements with a type attribute in the Search state
input elements with a type attribute in the Telephone state
textarea elements
select elements
- Numeric
input elements with a type attribute in the Hidden state
input elements with a type attribute in the Text state
input elements with a type attribute in the Search state
input elements with a type attribute in the Number state
textarea elements
select elements
- Month
input elements with a type attribute in the Hidden state
input elements with a type attribute in the Text state
input elements with a type attribute in the Search state
input elements with a type attribute in the Month state
textarea elements
select elements
- Date
input elements with a type attribute in the Hidden state
input elements with a type attribute in the Text state
input elements with a type attribute in the Search state
input elements with a type attribute in the Date state
textarea elements
select elements
Address levels: The "address-level1" – "address-level4" fields are used to describe
the locality of the street address. Different locales have different numbers of levels. For
example, the US uses two levels (state and town), the UK uses one or two depending on the address
(the post town, and in some cases the locality), and China can use three (province, city,
district). The "address-level1" field
represents the widest administrative division. Different locales order the fields in different
ways; for example, in the US the town (level 2) precedes the state (level 1); while in Japan the
prefecture (level 1) precedes the city (level 2) which precedes the district (level 3). Authors
are encouraged to provide forms that are presented in a way that matches the country's conventions
(hiding, showing, and rearranging fields accordingly as the user changes the country).
Processing model
Each input element to which the autocomplete attribute applies, each select element, and each textarea element, has an
autofill hint set, an autofill scope, an autofill field name, and
an IDL-exposed autofill value.
The autofill field name specifies the specific kind of data expected in the field,
e.g. "street-address" or "cc-exp".
The autofill hint set identifies what address or contact information type the user
agent is to look at, e.g. "shipping fax" or "billing".
The autofill scope identifies the group of fields whose information concerns the
same subject, and consists of the autofill hint set with, if
applicable, the "section-*" prefix, e.g. "billing",
"section-parent shipping", or "section-child shipping
home".
These values are defined as the result of running the following algorithm:
If the element has no autocomplete attribute,
then jump to the step labeled default.
Let tokens be the result of splitting the attribute's value on spaces.
If tokens is empty, then jump to the step labeled
default.
Let index be the index of the last token in tokens.
-
If the indexth token in tokens is not an ASCII
case-insensitive match for one of the tokens given in the first column of the following
table, or if the number of tokens in tokens is greater than the maximum
number given in the cell in the second column of that token's row, then jump to the step labeled
default. Otherwise, let field be the string given in the cell of the
first column of the matching row, and let category be the value of the cell
in the third column of that same row.
If category is Off or Automatic but the element's autocomplete attribute is wearing the autofill anchor
mantle, then jump to the step labeled default.
If category is Off, let the element's autofill field name
be the string "off", let its autofill hint set be empty, and
let its IDL-exposed autofill value be the string "off". Then,
abort these steps.
If category is Automatic, let the element's autofill field
name be the string "on", let its autofill hint set be
empty, and let its IDL-exposed autofill value be the string "on". Then, abort these steps.
Let scope tokens be an empty list.
Let hint tokens be an empty set.
Let IDL value have the same value as field.
If the indexth token in tokens is the first entry,
then skip to the step labeled done.
Decrement index by one.
-
If category is Contact and the indexth token in tokens is an ASCII case-insensitive match for one of the strings in
the following list, then run the substeps that follow:
The substeps are:
Let contact be the matching string from the list above.
Insert contact at the start of scope
tokens.
Add contact to hint tokens.
Let IDL value be the concatenation of contact, a
U+0020 SPACE character, and the previous value of IDL value (which at this
point will always be field).
If the indexth entry in tokens is the first
entry, then skip to the step labeled done.
Decrement index by one.
-
If the indexth token in tokens is an ASCII
case-insensitive match for one of the strings in the following list, then run the
substeps that follow:
The substeps are:
Let mode be the matching string from the list above.
Insert mode at the start of scope
tokens.
Add mode to hint tokens.
Let IDL value be the concatenation of mode, a
U+0020 SPACE character, and the previous value of IDL value (which at this
point will either be field or the concatenation of contact, a space, and field).
If the indexth entry in tokens is the first
entry, then skip to the step labeled done.
Decrement index by one.
If the indexth entry in tokens is not the first entry, then jump to
the step labeled default.
If the first eight characters of the indexth token in tokens are not
an ASCII case-insensitive match for the string "section-", then jump to the step labeled
default.
Let section be the indexth token in tokens,
converted to ASCII lowercase.
Insert section at the start of scope tokens.
Let IDL value be the concatenation of section, a U+0020 SPACE
character, and the previous value of IDL value.
Done: Let the element's autofill hint set be hint
tokens.
Let the element's autofill scope be scope tokens.
Let the element's autofill field name be field.
Let the element's IDL-exposed autofill value be IDL value.
Abort these steps.
Default: Let the element's IDL-exposed autofill value be the empty
string, and its autofill hint set and autofill scope be empty.
If the element's autocomplete attribute is
wearing the autofill anchor mantle, then let the element's autofill field
name be the empty string and abort these steps.
Let form be the element's form owner, if any, or null
otherwise.
-
If form is not null and form's autocomplete attribute is in the off state, then let the element's
autofill field name be "off".
Otherwise, let the element's autofill field name be "on".
For the purposes of autofill, a control's data depends on the kind of control:
- An
input element with its type attribute
in the E-mail state and with the multiple attribute specified - The element's values.
- Any other
input element - A
textarea element - The element's value.
- A
select element with its multiple
attribute specified - The
option elements in the select element's list of options that have their selectedness set to true. - Any other
select element - The
option element in the select element's list of options that has its selectedness set to true.
How to process the autofill hint set, autofill scope, and
autofill field name depends on the mantle that the autocomplete attribute is wearing.
- When wearing the autofill expectation mantle...
-
When an element's autofill field name is "off", the user agent should not remember the control's
data, and should not offer past values to the user.
In addition, when an element's autofill field name is "off", values are reset
when traversing the history.
Banks frequently do not want UAs to prefill login information:
<p><label>Account: <input type="text" name="ac" autocomplete="off"></label></p>
<p><label>PIN: <input type="password" name="pin" autocomplete="off"></label></p>
When an element's autofill field name is not "off", the user agent may store the control's
data, and may offer previously stored values to the user.
For example, suppose a user visits a page with this control:
<select name="country">
<option>Afghanistan
<option>Albania
<option>Algeria
<option>Andorra
<option>Angola
<option>Antigua and Barbuda
<option>Argentina
<option>Armenia
<!-- ... -->
<option>Yemen
<option>Zambia
<option>Zimbabwe
</select>
This might render as follows:
Suppose that on the first visit to this page, the user selects "Zambia". On the second visit,
the user agent could duplicate the entry for Zambia at the top of the list, so that the interface
instead looks like this:
When the autofill field name is "on", the user agent should attempt to use heuristics to
determine the most appropriate values to offer the user, e.g. based on the element's name value, the position of the element in the document's DOM, what
other fields exist in the form, and so forth.
When the autofill field name is one of the names of the autofill fields described above, the user agent should provide suggestions that
match the meaning of the field name as given in the table earlier in this section. The
autofill hint set should be used to select amongst multiple possible suggestions.
For example, if a user once entered one address into fields that used the
"shipping" keyword, and another address into
fields that used the "billing" keyword, then in
subsequent forms only the first address would be suggested for form controls whose autofill
hint set contains the keyword "shipping". Both addresses might be suggested,
however, for address-related form controls whose autofill hint set does not contain
either keyword.
- When wearing the autofill anchor mantle...
-
When the autofill field name is not the empty string, then the user agent must
act as if the user had specified the control's data for the given autofill
hint set, autofill scope, and autofill field name
combination.
When the user agent autofills form controls, elements
with the same form owner and the same autofill scope must use data
relating to the same person, address, payment instrument, and contact details. When a user agent autofills "country" and "country-name" fields with the same form
owner and autofill scope, and the user agent has a value for the country" field(s), then the "country-name" field(s) must be filled using a
human-readable name for the same country. When a user agent fills in multiple fields at
once, all fields with the same autofill field name, form owner and
autofill scope must be filled with the same value.
Suppose a user agent knows of two phone numbers, +1 555 123 1234 and +1 555 666
7777. It would not be conforming for the user agent to fill a field with autocomplete="shipping tel-local-prefix" with the value "123" and another field
in the same form with autocomplete="shipping tel-local-suffix" with the
value "7777". The only valid prefilled values given the aforementioned information would be "123"
and "1234", or "666" and "7777", respectively.
Similarly, if a form for some reason contained both a "cc-exp" field and a "cc-exp-month" field, and the user agent
prefilled the form, then the month component of the former would have to match the latter.
This requirement interacts with the autofill anchor mantle also. Consider the
following markup snippet:
<form>
<input type=hidden autocomplete="nickname" value="TreePlate">
<input type=text autocomplete="nickname">
</form>
The only value that a conforming user agent could suggest in the text field is
"TreePlate", the value given by the hidden input element.
The "section-*" tokens in the autofill scope are opaque;
user agents must not attempt to derive meaning from the precise values of these tokens.
For example, it would not be conforming if the user agent decided that it
should offer the address it knows to be the user's daughter's address for "section-child" and the addresses it knows to be the user's spouses' addresses for
"section-spouse".
The autocompletion mechanism must be implemented by the user agent acting as if the user had
modified the control's data, and must be done at a time where the element is mutable (e.g. just after the element has been inserted into the
document, or when the user agent stops parsing). User agents
must only prefill controls using values that the user could have entered.
For example, if a select element only has option
elements with values "Steve" and "Rebecca", "Jay", and "Bob", and has an autofill field
name "given-name", but the user
agent's only idea for what to prefill the field with is "Evan", then the user agent cannot prefill
the field. It would not be conforming to somehow set the select element to the value
"Evan", since the user could not have done so themselves.
A user agent prefilling a form control's value must not
cause that control to suffer from a type
mismatch, suffer from being too long,
suffer from being too short, suffer from an underflow, suffer from an overflow, or suffer from a step mismatch. Except when autofilling for requestAutocomplete(), a user agent prefilling a form
control's value must not cause that control to suffer from a pattern mismatch either. Where
possible given the control's constraints, user agents must use the format given as canonical in
the aforementioned table. Where it's not possible for the canonical format to be used, user agents
should use heuristics to attempt to convert values so that they can be used.
For example, if the user agent knows that the user's middle name is "Ines", and attempts to
prefill a form control that looks like this:
<input name=middle-initial maxlength=1 autocomplete="additional-name">
...then the user agent could convert "Ines" to "I" and prefill it that way.
A more elaborate example would be with month values. If the user agent knows that the user's
birthday is the 27th of July 2012, then it might try to prefill all of the following controls
with slightly different values, all driven from this information:
<input name=b type=month autocomplete="bday">
|
2012-07
|
The day is dropped since the Month state only accepts a
month/year combination.
|
<select name=c autocomplete="bday">
<option>Jan
<option>Feb
...
<option>Jul
<option>Aug
...
</select>
|
July
|
The user agent picks the month from the listed options, either by noticing there are twelve
options and picking the 7th, or by recognising that one of the strings (three characters "Jul"
followed by a newline and a space) is a close match for the name of the month (July) in one of
the user agent's supported languages, or through some other similar mechanism.
|
<input name=a type=number min=1 max=12 autocomplete="bday-month">
|
7
|
User agent converts "July" to a month number in the range 1..12, like the field.
|
<input name=a type=number min=0 max=11 autocomplete="bday-month">
|
6
|
User agent converts "July" to a month number in the range 0..11, like the field.
|
<input name=a type=number min=1 max=11 autocomplete="bday-month">
|
|
User agent doesn't fill in the field, since it can't make a good guess as to what the form expects.
|
A user agent may allow the user to override an element's autofill field name, e.g.
to change it from "off" to "on" to allow values to be remembered and prefilled despite
the page author's objections, or to always "off",
never remembering values.
More specifically, user agents may in particular consider replacing the autofill field
name of form controls that match the description given in the first column of the following
table, when their autofill field name is either "on" or "off", with the value given in the second cell of that
row. If this table is used, the replacements must be done in tree order, since all
but the first row references the autofill field name of earlier elements. When the
descriptions below refer to form controls being preceded or followed by others, they mean in the
list of listed elements that share the same form owner.
The autocomplete IDL attribute, on getting,
must return the element's IDL-exposed autofill value, and on setting, must
reflect the content attribute of the same name.
User interface for bulk autofill
When the requestAutocomplete()
method on a form element is invoked, the user agent must run the following steps:
Let form be the element on which the method was invoked.
-
If any of the following conditions are met, then queue a task to fail the
autofill request on form with the reason "disabled", and abort these steps:
the algorithm is not
form's node document is not fully
active
form's autocomplete
attribute is in the off state
the user has disabled this feature for this form's
node document's origin
the user agent does not support this form's fields (e.g. the form
has different fields whose autofill scope use different "section-*" tokens)
the form was obtained via unencrypted channels and the user agent
does not support autofill in such situations
another instance of this algorithm is already being run for form
User agents are encouraged to log the precise cause in a developer console, to
aid debugging.
Let pending autofills be an initially empty list of submittable elements, each annotated with a string known as the
original autocomplete value.
-
For each element that matches the following criteria, add the element to pending autofills, with the original autocomplete value annotation being
the value of the element's autocomplete
attribute:
Return, but continue running these steps in parallel.
Provide an interface for the user to efficiently fill in some or all of the fields listed
in pending autofills. Await the user's input. The user agent may include additional
(immutable) information, e.g. data obtained from elements
with an autocomplete attribute wearing the
autofill anchor mantle.
-
Queue a task to run the following steps:
-
If any of the following conditions are met, then fail the autofill request on
form with the reason "disabled", and abort these steps:
Again, user agents are encouraged to log the precise cause in a developer
console, to aid debugging.
If the user canceled the operation, fail the autofill request on form with the reason "cancel", and abort these steps.
-
For each element in pending autofills, run the following steps:
Let candidate be the element in question.
Let old autocomplete value be the original autocomplete
value annotation associated with candidate in pending
autofills.
-
If all of the following conditions are met, then autofill candidate:
-
Statically validate the constraints of form. If the
result was negative, then fail the autofill request on form
with the reason "invalid", and abort
these steps.
Statically validating the
constraints of a form involves firing invalid events to each control that does not satisfy its contraints.
Fire a simple event that bubbles named autocomplete at form.
When the user agent is required to fail the autofill request on a form
element target with a reason reason, the user agent must
dispatch an event that uses the AutocompleteErrorEvent interface, with the event type
autocompleteerror, which bubbles, is not cancelable, has no default action,
has its reason attribute set to reason, and which is trusted, at target.
The task source for the tasks mentioned in this
section is the DOM manipulation task source.
enum AutocompleteErrorReason { "" /* empty string */, "cancel", "disabled", "invalid" };
[Constructor(DOMString type, optional AutocompleteErrorEventInit eventInitDict)]
interface AutocompleteErrorEvent : Event {
readonly attribute AutocompleteErrorReason reason;
};
dictionary AutocompleteErrorEventInit : EventInit {
AutocompleteErrorReason reason;
};
- event .
reason -
For the autocompleteerror event, returns the
general reason for the failure of the requestAutocomplete() method, from the list
below.
The defined reason codes are:
- "
Reason is unknown.
- "
cancel" The user canceled the autofill interface.
- "
disabled" -
The autofill interface is disabled for this form.
There are many reasons why this might be the case; the precise reason is not given, to
protect the user's privacy. Amongst these reasons are such factors as:
The page being delivered over an unencrypted connection (susceptible to
man-in-the-middle attacks), when the user agent does not want to risk the user's information
being provided to an attacker.
The form having a combination of fields for which the user agent does not have a
dedicated autofill interface.
The form's autocomplete attribute being in
the off state.
The user having disabled the feature.
- "
invalid" The fields have been prefilled, but at least one of the controls in the form does not
satisfy its constraints.
The reason attribute must
return the value it was initialised to. When the object is created, this attribute must be
initialised to the empty string. It
represents the context information for the event.
APIs for the text field selections
The input and textarea elements define the following members in their
DOM interfaces for handling their selection:
The setRangeText method uses the following
enumeration:
enum SelectionMode {
"select",
"start",
"end",
"preserve", // default
};
These methods and attributes expose and control the selection of input and
textarea text fields.
- element .
select() -
Selects everything in the text field.
- element .
selectionStart [ = value ] -
Returns the offset to the start of the selection.
Can be set, to change the start of the selection.
- element .
selectionEnd [ = value ] -
Returns the offset to the end of the selection.
Can be set, to change the end of the selection.
- element .
selectionDirection [ = value ] -
Returns the current direction of the selection.
Can be set, to change the direction of the selection.
The possible values are "forward", "backward", and "none".
- element .
setSelectionRange(start, end [, direction] ) -
Changes the selection to cover the given substring in the given direction. If the direction
is omitted, it will be reset to be the platform default (none or forward).
- element .
setRangeText(replacement [, start, end [, selectionMode ] ] ) -
Replaces a range of text with the new text. If the start and end arguments are not provided, the range is assumed to be the selection.
The final argument determines how the selection should be set after the text has been
replaced. The possible values are:
- "
select" - Selects the newly inserted text.
- "
start" - Moves the selection to just before the inserted text.
- "
end" - Moves the selection to just after the selected text.
- "
preserve" - Attempts to preserve the selection. This is the default.
For input elements, calling these methods while they don't apply, and getting or setting these attributes while they don't apply, must throw an InvalidStateError exception. Otherwise, they
must act as described below.
For input elements, these methods and attributes must operate on the element's
value. For textarea elements, these methods and
attributes must operate on the element's raw
value.
Where possible, user interface features for changing the text selection in input
and textarea elements must be implemented in terms of the DOM API described in this
section, so that, e.g., all the same events fire.
The selections of input and textarea elements have a
direction, which is either forward, backward, or none. This direction
is set when the user manipulates the selection. The exact meaning of the selection direction
depends on the platform.
On Windows, the direction indicates the position of the caret relative to the
selection: a forward selection has the caret at the end of the selection and a
backward selection has the caret at the start of the selection. Windows has no none
direction. On Mac, the direction indicates which end of the selection is affected when the user
adjusts the size of the selection using the arrow keys with the Shift modifier: the forward
direction means the end of the selection is modified, and the backwards direction means the start
of the selection is modified. The none direction is the default on Mac, it indicates that no
particular direction has yet been selected. The user sets the direction implicitly when first
adjusting the selection, based on which directional arrow key was used.
The select() method must cause the
contents of the text field to be fully selected, with the selection direction being none, if the
platform support selections with the direction none, or otherwise forward. The user
agent must then queue a task to fire a simple event that bubbles named
select at the element, using the user interaction task
source as the task source.
In the case of input elements, if the control has no text field, then the method
must do nothing.
For instance, in a user agent where <input type=color> is rendered as a colour well with a
picker, as opposed to a text field accepting a hexadecimal colour code, there would be no text
field, and thus nothing to select, and thus calls to the method are ignored.
The selectionStart attribute
must, on getting, return the offset (in logical order) to the character that immediately follows
the start of the selection. If there is no selection, then it must return the offset (in logical
order) to the character that immediately follows the text entry cursor.
On setting, it must act as if the setSelectionRange() method had been called,
with the new value as the first argument; the current value of the selectionEnd attribute as the second argument,
unless the current value of the selectionEnd
is less than the new value, in which case the second argument must also be the new value; and the
current value of the selectionDirection
as the third argument.
The selectionEnd attribute
must, on getting, return the offset (in logical order) to the character that immediately follows
the end of the selection. If there is no selection, then it must return the offset (in logical
order) to the character that immediately follows the text entry cursor.
On setting, it must act as if the setSelectionRange() method had been called,
with the current value of the selectionStart attribute as the first argument,
the new value as the second argument, and the current value of the selectionDirection as the third argument.
The selectionDirection
attribute must, on getting, return the string corresponding to the current selection direction: if
the direction is forward, "forward"; if the direction is
backward, "backward"; and otherwise, "none".
On setting, it must act as if the setSelectionRange() method had been called,
with the current value of the selectionStart attribute as the first argument,
the current value of the selectionEnd
attribute as the second argument, and the new value as the third argument.
The setSelectionRange(start, end, direction) method
must set the selection of the text field to the sequence of characters starting with the character
at the startth position (in logical order) and ending with the character at
the (end-1)th position. Arguments greater than the
length of the value of the text field must be treated as pointing at the end of the text field. If
end is less than or equal to start then the start of the
selection and the end of the selection must both be placed immediately before the character with
offset end. In UAs where there is no concept of an empty selection, this must
set the cursor to be just before the character with offset end. The direction
of the selection must be set to backward if direction is a
case-sensitive match for the string "backward", forward
if direction is a case-sensitive match for the string "forward" or if the platform does not support selections with the direction
none, and none otherwise (including if the argument is omitted). The user agent must
then queue a task to fire a simple event that bubbles named select at the element, using the user interaction task
source as the task source.
The setRangeText(replacement, start, end, selectMode) method must run the following steps:
-
If the method has only one argument, then let start and end have the values of the selectionStart attribute and the selectionEnd attribute respectively.
Otherwise, let start, end have the values of the
second and third arguments respectively.
If start is greater than end, then throw an
IndexSizeError exception and abort these steps.
If start is greater than the length of the value of the text field,
then set it to the length of the value of the text field.
If end is greater than the length of the value of the text field,
then set it to the length of the value of the text field.
Let selection start be the current value of the selectionStart attribute.
Let selection end be the current value of the selectionEnd attribute.
If start is less than end, delete the sequence of
characters starting with the character at the startth position (in logical
order) and ending with the character at the (end-1)th
position.
Insert the value of the first argument into the text of the value of the text field,
immediately before the startth character.
Let new length be the length of the value of the first argument.
Let new end be the sum of start and new length.
-
Run the appropriate set of substeps from the following list:
- If the fourth argument's value is "
select" -
Let selection start be start.
Let selection end be new end.
- If the fourth argument's value is "
start" -
Let selection start and selection end be start.
- If the fourth argument's value is "
end" -
Let selection start and selection end be new end.
- If the fourth argument's value is "
preserve" (the default) -
Let old length be end minus start.
Let delta be new length minus old length.
-
If selection start is greater than end, then
increment it by delta. (If delta is negative, i.e.
the new text is shorter than the old text, then this will decrease the value of
selection start.)
Otherwise: if selection start is greater than start, then set it to start. (This snaps the start of the
selection to the start of the new text if it was in the middle of the text that it
replaced.)
-
If selection end is greater than end, then
increment it by delta in the same way.
Otherwise: if selection end is greater than start, then set it to new end. (This snaps the end of the
selection to the end of the new text if it was in the middle of the text that it
replaced.)
-
Set the selection of the text field to the sequence of characters starting with the character
at the selection startth position (in logical order) and ending with the
character at the (selection end-1)th position. In UAs
where there is no concept of an empty selection, this must set the cursor to be just before the
character with offset end. The direction of the selection must be set to
forward if the platform does not support selections with the direction none, and
none otherwise.
Queue a task to fire a simple event that bubbles named select at the element, using the user interaction task
source as the task source.
All elements to which this API applies have either a
selection or a text entry cursor position at all times (even for elements that are not being
rendered). User agents should follow platform conventions to determine their initial
state.
Characters with no visible rendering, such as U+200D ZERO WIDTH JOINER, still count as
characters. Thus, for instance, the selection can include just an invisible character, and the
text insertion cursor can be placed to one side or another of such a character.
To obtain the currently selected text, the following JavaScript suffices:
var selectionText = control.value.substring(control.selectionStart, control.selectionEnd);
...where control is the input or textarea
element.
To add some text at the start of a text control, while maintaining the text selection, the
three attributes must be preserved:
var oldStart = control.selectionStart;
var oldEnd = control.selectionEnd;
var oldDirection = control.selectionDirection;
var prefix = "http://";
control.value = prefix + control.value;
control.setSelectionRange(oldStart + prefix.length, oldEnd + prefix.length, oldDirection);
...where control is the input or textarea
element.
Constraints
Definitions
A submittable element is a candidate for constraint
validation except when a condition has barred
the element from constraint validation. (For example, an element is barred from
constraint validation if it is an object element.)
An element can have a custom validity error message defined. Initially, an element
must have its custom validity error message set to the empty string. When its value
is not the empty string, the element is suffering from a custom error. It can be set
using the setCustomValidity() method. The user
agent should use the custom validity error message when alerting the user to the
problem with the control.
An element can be constrained in various ways. The following is the list of validity
states that a form control can be in, making the control invalid for the purposes of
constraint validation. (The definitions below are non-normative; other parts of this specification
define more precisely when each state applies or does not.)
- Suffering from being missing
-
When a control has no value but has a required attribute (input required, textarea required); or, in the case of an element in a radio button group, any of the other elements in the group has a
required attribute; or, for select
elements, none of the option elements have their selectedness set (select required).
- Suffering from a type mismatch
-
When a control that allows arbitrary user input has a value that is not in the correct syntax (E-mail, URL).
- Suffering from a pattern mismatch
-
When a control has a value that doesn't satisfy the
pattern attribute.
- Suffering from being too long
-
When a control has a value that is too long for the
form control maxlength attribute
(input maxlength, textarea
maxlength).
- Suffering from being too short
-
When a control has a value that is too short for the
form control minlength attribute
(input minlength, textarea
minlength).
- Suffering from an underflow
-
When a control has a value that is too low for the
min attribute.
- Suffering from an overflow
-
When a control has a value that is too high for the
max attribute.
- Suffering from a step mismatch
-
When a control has a value that doesn't fit the
rules given by the step attribute.
- Suffering from bad input
-
When a control has incomplete input and the user agent does not think the user ought to
be able to submit the form in its current state.
- Suffering from a custom error
-
When a control's custom validity error message (as set by the element's
setCustomValidity() method) is not the empty
string.
An element can still suffer from these states even when the element is disabled; thus these states can be represented in the DOM even
if validating the form during submission wouldn't indicate a problem to the user.
An element satisfies its constraints if it is not suffering
from any of the above validity states.
Constraint validation
When the user agent is required to statically validate the constraints of
form element form, it must run the following steps, which return
either a positive result (all the controls in the form are valid) or a negative
result (there are invalid controls) along with a (possibly empty) list of elements that are
invalid and for which no script has claimed responsibility:
Let controls be a list of all the submittable elements whose form owner is form, in tree order.
Let invalid controls be an initially empty list of elements.
-
For each element field in controls, in tree
order, run the following substeps:
If field is not a candidate for constraint validation,
then move on to the next element.
Otherwise, if field satisfies its
constraints, then move on to the next element.
Otherwise, add field to invalid
controls.
If invalid controls is empty, then return a positive result and
abort these steps.
Let unhandled invalid controls be an initially empty list of
elements.
-
For each element field in invalid controls, if any,
in tree order, run the following substeps:
Fire a simple event named invalid that
is cancelable at field.
If the event was not canceled, then add field to unhandled invalid controls.
Return a negative result with the list of elements in the unhandled
invalid controls list.
If a user agent is to interactively validate the constraints of form
element form, then the user agent must run the following steps:
Statically validate the constraints of form, and let
unhandled invalid controls be the list of elements returned if the result was
negative.
If the result was positive, then return that result and abort these steps.
Report the problems with the constraints of at least one of the elements given in
unhandled invalid controls to the user. User agents may focus one of those elements in
the process, by running the focusing steps for that element, and may change the
scrolling position of the document, or perform some other action that brings the element to the
user's attention. User agents may report more than one constraint violation. User agents may
coalesce related constraint violation reports if appropriate (e.g. if multiple radio buttons in a
group are marked as required, only one error need be
reported). If one of the controls is not being rendered (e.g. it has the hidden attribute set) then user agents may report a script
error.
Return a negative result.
The constraint validation API
- element .
willValidate -
Returns true if the element will be validated when the form is submitted; false
otherwise.
- element .
setCustomValidity(message) -
Sets a custom error, so that the element would fail to validate. The given message is the
message to be shown to the user when reporting the problem to the user.
If the argument is the empty string, clears the custom error.
- element .
validity . valueMissing -
Returns true if the element has no value but is a required field; false otherwise.
- element .
validity . typeMismatch -
Returns true if the element's value is not in the correct syntax; false otherwise.
- element .
validity . patternMismatch -
Returns true if the element's value doesn't match the provided pattern; false otherwise.
- element .
validity . tooLong -
Returns true if the element's value is longer than the provided maximum length; false otherwise.
- element .
validity . tooShort -
Returns true if the element's value, if it is not the empty string, is shorter than the
provided minimum length; false otherwise.
- element .
validity . rangeUnderflow -
Returns true if the element's value is lower than the provided minimum; false otherwise.
- element .
validity . rangeOverflow -
Returns true if the element's value is higher than the provided maximum; false otherwise.
- element .
validity . stepMismatch -
Returns true if the element's value doesn't fit the rules given by the step attribute; false otherwise.
- element .
validity . badInput -
Returns true if the user has provided input in the user interface that the user agent is
unable to convert to a value; false otherwise.
- element .
validity . customError -
Returns true if the element has a custom error; false otherwise.
- element .
validity . valid -
Returns true if the element's value has no validity problems; false otherwise.
- valid = element .
checkValidity() -
Returns true if the element's value has no validity problems; false otherwise. Fires an invalid event at the element in the latter case.
- valid = element .
reportValidity() -
Returns true if the element's value has no validity problems; otherwise, returns false, fires
an invalid event at the element, and (if the event isn't
canceled) reports the problem to the user.
- element .
validationMessage -
Returns the error message that would be shown to the user if the element was to be checked
for validity.
The willValidate attribute must return
true if an element is a candidate for constraint validation, and false otherwise
(i.e. false if any conditions are barring it from
constraint validation).
The setCustomValidity(message), when invoked, must set the custom validity error
message to the value of the given message argument.
In the following example, a script checks the value of a form control each time it is edited,
and whenever it is not a valid value, uses the setCustomValidity() method to set an appropriate
message.
<label>Feeling: <input name=f type="text" oninput="check(this)"></label>
<script>
function check(input) {
if (input.value == "good" ||
input.value == "fine" ||
input.value == "tired") {
input.setCustomValidity('"' + input.value + '" is not a feeling.');
} else {
// input is fine -- reset the error message
input.setCustomValidity('');
}
}
</script>
The validity attribute must return a
ValidityState object that represents the validity states of the element.
This object is live.
interface ValidityState {
readonly attribute boolean valueMissing;
readonly attribute boolean typeMismatch;
readonly attribute boolean patternMismatch;
readonly attribute boolean tooLong;
readonly attribute boolean tooShort;
readonly attribute boolean rangeUnderflow;
readonly attribute boolean rangeOverflow;
readonly attribute boolean stepMismatch;
readonly attribute boolean badInput;
readonly attribute boolean customError;
readonly attribute boolean valid;
};
A ValidityState object has the following attributes. On getting, they must return
true if the corresponding condition given in the following list is true, and false otherwise.
valueMissing-
The control is suffering from being missing.
typeMismatch-
The control is suffering from a type mismatch.
patternMismatch-
The control is suffering from a pattern mismatch.
tooLong-
The control is suffering from being too long.
tooShort-
The control is suffering from being too short.
rangeUnderflow-
The control is suffering from an underflow.
rangeOverflow-
The control is suffering from an overflow.
stepMismatch-
The control is suffering from a step mismatch.
badInput-
The control is suffering from bad input.
customError-
The control is suffering from a custom error.
valid-
None of the other conditions are true.
When the checkValidity() method is
invoked, if the element is a candidate for constraint validation and does not satisfy its constraints, the user agent must fire a simple
event named invalid that is cancelable (but in this case
has no default action) at the element and return false. Otherwise, it must only return true
without doing anything else.
When the reportValidity() method is
invoked, if the element is a candidate for constraint validation and does not satisfy its constraints, the user agent must: fire a simple
event named invalid that is cancelable at the element,
and if that event is not canceled, report the problems with the constraints of that element to the
user; then, return false. Otherwise, it must only return true without doing anything else. When
reporting the problem with the constraints to the user, the user agent may run the focusing
steps for that element, and may change the scrolling position of the document, or perform
some other action that brings the element to the user's attention. User agents may report more
than one constraint violation, if the element suffers from multiple problems at once. If the
element is not being rendered, then the user agent may, instead of notifying the
user, report a script error.
The validationMessage attribute must
return the empty string if the element is not a candidate for constraint validation
or if it is one but it satisfies its constraints; otherwise,
it must return a suitably localised message that the user agent would show the user if this were
the only form control with a validity constraint problem. If the user agent would not actually
show a textual message in such a situation (e.g. it would show a graphical cue instead), then the
attribute must return a suitably localised message that expresses (one or more of) the validity
constraint(s) that the control does not satisfy. If the element is a candidate for
constraint validation and is suffering from a custom error, then the
custom validity error message should be present in the return value.
Security
Servers should not rely on client-side validation. Client-side validation can
be intentionally bypassed by hostile users, and unintentionally bypassed by users of older user
agents or automated tools that do not implement these features. The constraint validation features
are only intended to improve the user experience, not to provide any kind of security
mechanism.
Form submission
Introduction
This section is non-normative.
When a form is submitted, the data in the form is converted into the structure specified by the
enctype, and then sent to the destination specified by the
action using the given method.
For example, take the following form:
<form action="/find.cgi" method=get>
<input type=text name=t>
<input type=search name=q>
<input type=submit>
</form>
If the user types in "cats" in the first field and "fur" in the second, and then hits the
submit button, then the user agent will load /find.cgi?t=cats&q=fur.
On the other hand, consider this form:
<form action="/find.cgi" method=post enctype="multipart/form-data">
<input type=text name=t>
<input type=search name=q>
<input type=submit>
</form>
Given the same user input, the result on submission is quite different: the user agent instead
does an HTTP POST to the given URL, with as the entity body something like the following text:
------kYFrd4jNJEgCervE
Content-Disposition: form-data; name="t"
cats
------kYFrd4jNJEgCervE
Content-Disposition: form-data; name="q"
fur
------kYFrd4jNJEgCervE--
Implicit submission
A form element's default button is the first submit button in tree order whose form
owner is that form element.
If the user agent supports letting the user submit a form implicitly (for example, on some
platforms hitting the "enter" key while a text field is focused implicitly submits the form), then
doing so for a form whose default button has a defined activation
behaviour must cause the user agent to run synthetic click activation steps on
that default button.
Consequently, if the default button is disabled, the form is not submitted when such an implicit
submission mechanism is used. (A button has no activation behaviour when
disabled.)
There are pages on the Web that are only usable if there is a way to implicitly
submit forms, so user agents are strongly encouraged to support this.
If the form has
no submit button, then the implicit submission
mechanism must do nothing if the form has more than one field that blocks implicit
submission, and must submit the form
element from the form element itself otherwise.
For the purpose of the previous paragraph, an element is a field that blocks implicit
submission of a form element if it is an input element whose
form owner is that form element and whose type attribute is in one of the following states:
Text,
Search,
URL,
Telephone,
E-mail,
Password,
Date and Time,
Date,
Month,
Week,
Time,
Number
Form submission algorithm
When a form element form is submitted from an element submitter
(typically a button), optionally with a submitted from submit() method flag set, the user agent must run the
following steps:
Let form document be the form's
node document.
If form document has no associated
browsing context or its active sandboxing flag set has its
sandboxed forms browsing context flag set, then abort these steps without doing
anything.
Let form browsing context be the browsing context of form document.
If the submitted from submit()
method flag is not set, and the submitter element's no-validate state is false, then interactively
validate the constraints of form and examine the result: if the result
is negative (the constraint validation concluded that there were invalid fields and probably
informed the user of this) then fire a simple event named invalid at the form element and then abort these
steps.
If the submitted from submit()
method flag is not set, then fire a simple event that bubbles and is
cancelable named submit, at form. If the
event's default action is prevented (i.e. if the event is canceled) then abort these steps.
Otherwise, continue (effectively the default action is to perform the submission).
Let form data set be the result of constructing the form data
set for form in the context of submitter.
Let action be the submitter element's action.
-
If action is the empty string, let action be
the document's address of the form document.
Resolve the URL action, relative to the submitter element. If this fails,
abort these steps.
Let action be the resulting absolute URL.
Let action components be the resulting parsed
URL.
Let scheme be the scheme of
the resulting parsed URL.
Let enctype be the submitter element's enctype.
Let method be the submitter element's method.
Let target be the submitter element's target.
If the user indicated a specific browsing context to use when submitting the
form, then let target browsing context be that browsing context.
Otherwise, apply the rules for choosing a browsing context given a browsing context
name using target as the name and form browsing
context as the context in which the algorithm is executed, and let target
browsing context be the resulting browsing context.
If target browsing context was created in the previous step, or,
alternatively, if the form document has not yet completely
loaded and the submitted from submit()
method flag is set, then let replace be true. Otherwise, let it be
false.
-
If the value of method is dialog then jump to the submit
dialog steps.
Otherwise, select the appropriate row in the table below based on the value of scheme as given by the first cell of each row. Then, select the appropriate cell
on that row based on the value of method as given in the first cell of each
column. Then, jump to the steps named in that cell and defined below the table.
If scheme is not one of those listed in this table, then the behaviour is
not defined by this specification. User agents should, in the absence of another specification
defining this, act in a manner analogous to that defined in this specification for similar
schemes.
Each form element has a planned navigation, which is either null or a
task; when the form is first created, its
planned navigation must be set to null. In the behaviours described below, when the
user agent is required to plan to navigate to a particular resource destination, it must run the following steps:
If the form has a non-null planned navigation, remove it from
its task queue.
-
Let the form's planned navigation be a new task that consists of running the following steps:
Let the form's planned navigation be null.
Navigate target browsing context to
the particular resource destination. If replace is
true, then target browsing context must be navigated with
replacement enabled.
For the purposes of this task, target browsing context and replace are the variables that were set up when the overall form submission
algorithm was run, with their values as they stood when this planned navigation
was queued.
-
Queue the task that is the form's new
planned navigation.
The task source for this task is the DOM manipulation task
source.
The behaviours are as follows:
- Mutate action URL
-
Let query be the result of encoding the form data
set using the application/x-www-form-urlencoded encoding
algorithm, interpreted as a US-ASCII string.
Set parsed action's query
component to query.
Let destination be a new URL formed by applying the
URL serialiser algorithm to parsed action.
Plan to navigate to destination.
- Submit as entity body
-
Let entity body be the result of encoding the form data
set using the appropriate form encoding algorithm.
Let MIME type be determined as follows:
- If enctype is
application/x-www-form-urlencoded - Let MIME type be "
application/x-www-form-urlencoded". - If enctype is
multipart/form-data - Let MIME type be the concatenation of the string "
multipart/form-data;", a U+0020 SPACE character, the string "boundary=", and the multipart/form-data boundary
string generated by the multipart/form-data encoding
algorithm. - If enctype is
text/plain - Let MIME type be "
text/plain".
Otherwise, plan to navigate to action using the HTTP
method given by method and with entity body as the
entity body, of type MIME type.
- Get action URL
-
Plan to navigate to action.
The form data set is discarded.
- Post to data:
-
Let data be the result of encoding the form data
set using the appropriate form encoding algorithm.
If action contains the string "%%%%" (four U+0025
PERCENT SIGN characters), then percent encode all bytes in data that, if interpreted as US-ASCII, are not characters in the URL
default encode set, and then, treating the result as a US-ASCII string,
UTF-8 percent encode all the U+0025 PERCENT SIGN characters in the resulting
string and replace the first occurrence of "%%%%" in action with the resulting doubly-escaped string. [[!URL]]
Otherwise, if action contains the string "%%"
(two U+0025 PERCENT SIGN characters in a row, but not four), then UTF-8 percent
encode all characters in data that, if interpreted as US-ASCII, are
not characters in the URL default encode set, and then, treating the result as a
US-ASCII string, replace the first occurrence of "%%" in action with the resulting escaped string. [[!URL]]
Plan to navigate to the potentially modified action (which
will be a data: URL).
-
-
Let headers be the resulting encoding the form data
set using the application/x-www-form-urlencoded encoding
algorithm, interpreted as a US-ASCII string.
Replace occurrences of U+002B PLUS SIGN characters (+) in headers with
the string "%20".
Let destination consist of all the characters from the first character
in action to the character immediately before the first U+003F QUESTION
MARK character (?), if any, or the end of the string if there are none.
Append a single U+003F QUESTION MARK character (?) to destination.
Append headers to destination.
Plan to navigate to destination.
- Mail as body
-
Let body be the resulting of encoding the form data
set using the appropriate form encoding algorithm and then percent encoding all the bytes in the resulting byte string
that, when interpreted as US-ASCII, are not characters in the URL default encode
set. [[!URL]]
Let destination have the same value as action.
If destination does not contain a U+003F QUESTION MARK character (?),
append a single U+003F QUESTION MARK character (?) to destination.
Otherwise, append a single U+0026 AMPERSAND character (&).
Append the string "body=" to destination.
Append body, interpreted as a US-ASCII string, to destination.
Plan to navigate to destination.
- Submit dialog
-
Let subject be the nearest ancestor dialog element of form, if any.
If there isn't one, or if it does not have an open
attribute, do nothing. Otherwise, proceed as follows:
If submitter is an input element whose type attribute is in the Image Button state, then let result
be the string formed by concatenating the selected coordinate's x-component, expressed as a base-ten number using ASCII digits, a
U+002C COMMA character (,), and the selected
coordinate's y-component, expressed in the same way as the x-component.
Otherwise, if submitter has a value, then let result be that value.
Otherwise, there is no result.
Then, close the dialog subject. If there is a result, let that be the return value.
The appropriate form encoding algorithm is
determined as follows:
- If enctype is
application/x-www-form-urlencoded - Use the
application/x-www-form-urlencoded encoding
algorithm. - If enctype is
multipart/form-data - Use the
multipart/form-data encoding algorithm. - If enctype is
text/plain - Use the
text/plain encoding algorithm.
Constructing the form data set
The algorithm to construct the form data set
for a form form optionally in the context of a submitter submitter is as follows. If not specified otherwise, submitter
is null.
Let controls be a list of all the submittable elements whose form owner is form, in tree order.
Let the form data set be a list of name-value-type tuples, initially
empty.
-
Loop: For each element field in controls, in
tree order, run the following substeps:
-
If any of the following conditions are met, then skip these substeps for this element:
- The field element has a
datalist element ancestor. - The field element is disabled.
- The field element is a button but
it is not submitter.
- The field element is an
input element whose type attribute is in the Checkbox state and whose checkedness is false. - The field element is an
input element whose type attribute is in the Radio Button state and whose checkedness is false. - The field element is not an
input element whose type attribute is in the Image Button state, and either the field element does not have a name attribute
specified, or its name attribute's value is the empty
string. - The field element is an
object element that is not using
a plugin.
Otherwise, process field as follows:
Let type be the value of the type IDL
attribute of field.
-
If the field element is an input element whose type attribute is in the Image Button state, then run these further nested
substeps:
If the field element has a name
attribute specified and its value is not the empty string, let name be
that value followed by a single U+002E FULL STOP character (.). Otherwise, let name be the empty string.
Let namex be the string consisting of the
concatenation of name and a single U+0078 LATIN SMALL LETTER X character
(x).
Let namey be the string consisting of the
concatenation of name and a single U+0079 LATIN SMALL LETTER Y character
(y).
The field element is submitter, and before
this algorithm was invoked the user indicated a coordinate. Let x be the x-component of the coordinate selected by the
user, and let y be the y-component of the coordinate
selected by the user.
Append an entry to the form data set with the name namex, the value x, and the type type.
Append an entry to the form data set with the name namey and the value y, and the type
type.
Skip the remaining substeps for this element: if there are any more elements in controls, return to the top of the loop step, otherwise, jump to the
end step below.
Let name be the value of the field element's
name attribute.
If the field element is a select element, then for each
option element in the select element's list of options whose selectedness is true and that is not disabled, append an entry to the form data
set with the name as the name, the value of the option element as the value, and
type as the type.
-
Otherwise, if the field element is an input element whose
type attribute is in the Checkbox state or the Radio Button state, then run these further nested
substeps:
If the field element has a value attribute specified, then let value
be the value of that attribute; otherwise, let value be the string "on".
Append an entry to the form data set with name
as the name, value as the value, and type as the
type.
Otherwise, if the field element is an input element
whose type attribute is in the File Upload state, then for each file selected in the input element,
append an entry to the form data set with the name as
the name, the file (consisting of the name, the type, and the body) as the value, and type as the type. If there are no selected files, then append an entry to the
form data set with the name as the name, the empty
string as the value, and application/octet-stream as the type.
Otherwise, if the field element is an object element:
try to obtain a form submission value from the plugin, and if that is successful,
append an entry to the form data set with name as the
name, the returned form submission value as the value, and the string "object" as the type.
Otherwise, append an entry to the form data set with name as the name, the value of the field element as the value, and type as the type.
-
If the element has a dirname attribute, and that
attribute's value is not the empty string, then run these substeps:
Let dirname be the value of the element's dirname attribute.
Let dir be the string "ltr" if the
directionality of the element is 'ltr', and "rtl" otherwise (i.e. when the directionality of the element is
'rtl').
Append an entry to the form data set with dirname as the name, dir as the value, and the string
"direction" as the type.
An element can only have a dirname
attribute if it is a textarea element or an input element whose
type attribute is in either the Text state or the Search state.
-
End: For the name of each entry in the form data set, and for the
value of each entry in the form data set whose type is not "file" or "textarea", replace every occurrence of a U+000D
CARRIAGE RETURN (CR) character not followed by a U+000A LINE FEED (LF) character, and every
occurrence of a U+000A LINE FEED (LF) character not preceded by a U+000D CARRIAGE RETURN (CR)
character, by a two-character string consisting of a U+000D CARRIAGE RETURN U+000A LINE FEED
(CRLF) character pair.
In the case of the value of
textarea elements, this newline normalization is already performed during the
conversion of the control's raw value into the
control's value (which also performs any necessary line
wrapping). In the case of input elements type
attributes in the File Upload state, the value is not
normalized.
Return the form data set.
Selecting a form submission encoding
If the user agent is to pick an encoding for a
form, optionally with an allow non-ASCII-compatible encodings flag set, it must run
the following substeps:
Let input be the value of the form element's accept-charset attribute.
Let candidate encoding labels be the result of splitting input on spaces.
Let candidate encodings be an empty list of character encodings.
For each token in candidate encoding labels in turn (in the order in
which they were found in input), get an
encoding for the token and, if this does not result in failure, append the
encoding to candidate encodings.
If the allow non-ASCII-compatible encodings flag is not set, remove any encodings
that are not ASCII-compatible character
encodings from candidate encodings.
If candidate encodings is empty, return UTF-8 and abort these
steps.
-
Each character encoding in candidate encodings can represent a finite
number of characters. (For example, UTF-8 can represent all 1.1 million or so Unicode code
points, while Windows-1252 can only represent 256.)
For each encoding in candidate encodings, determine how many of the
characters in the names and values of the entries in the form data set the
encoding can represent (without ignoring duplicates). Let max be the
highest such count. (For UTF-8, max would equal the number of characters
in the names and values of the entries in the form data set.)
Return the first encoding in candidate encodings that can encode max characters in the names and values of the entries in the form
data set.
URL-encoded form data
This form data set encoding is in many ways an aberrant monstrosity, the result of
many years of implementation accidents and compromises leading to a set of requirements necessary
for interoperability, but in no way representing good design practices. In particular, readers are
cautioned to pay close attention to the twisted details involving repeated (and in some cases
nested) conversions between character encodings and byte sequences.
The application/x-www-form-urlencoded encoding algorithm is as
follows:
Let result be the empty string.
-
If the form element has an accept-charset attribute, let the selected character
encoding be the result of picking an encoding for the form.
Otherwise, if the form element has no accept-charset attribute, but the document's
character encoding is an ASCII-compatible character encoding, then that is
the selected character encoding.
Otherwise, let the selected character encoding be UTF-8.
Let charset be the name of the
selected character encoding.
-
For each entry in the form data set, perform these substeps:
If the entry's name is "_charset_" and its
type is "hidden", replace its value with charset.
If the entry's type is "file", replace its value with the file's
name only.
For each character in the entry's name and value that cannot be expressed using the
selected character encoding, replace the character by a string consisting of a U+0026 AMPERSAND
character (&), a U+0023 NUMBER SIGN character (#), one or more ASCII digits
representing the Unicode code point of the character in base ten, and finally a U+003B
SEMICOLON character (;).
-
Encode the entry's name and value using the encoder for the selected character
encoding. The entry's name and value are now byte strings.
-
For each byte in the entry's name and value, apply the appropriate subsubsteps from the
following list:
- If the byte is 0x20 (U+0020 SPACE if interpreted as ASCII)
- Replace the byte with a single 0x2B byte (U+002B PLUS SIGN character (+) if interpreted
as ASCII).
- If the byte is in the range 0x2A, 0x2D, 0x2E, 0x30 to 0x39, 0x41 to 0x5A, 0x5F, 0x61 to
0x7A
Leave the byte as is.
- Otherwise
-
Let s be a string consisting of a U+0025 PERCENT SIGN character
(%) followed by uppercase ASCII hex digits representing the hexadecimal value
of the byte in question (zero-padded if necessary).
Encode the string s as US-ASCII, so that it is now a byte
string.
Replace the byte in question in the name or value being processed by the bytes in
s, preserving their relative order.
-
Interpret the entry's name and value as Unicode strings encoded in US-ASCII. (All of the
bytes in the string will be in the range 0x00 to 0x7F; the high bit will be zero throughout.)
The entry's name and value are now Unicode strings again.
If the entry's name is "isindex", its type is
"text", and this is the first entry in the form data
set, then append the value to result and skip the rest of the
substeps for this entry, moving on to the next entry, if any, or the next step in the overall
algorithm otherwise.
If this is not the first entry, append a single U+0026 AMPERSAND character (&) to
result.
Append the entry's name to result.
Append a single U+003D EQUALS SIGN character (=) to result.
Append the entry's value to result.
Encode result as US-ASCII and return the resulting byte
stream.
To decode
application/x-www-form-urlencoded payloads, the following algorithm should be
used. This algorithm uses as inputs the payload itself, payload, consisting of
a Unicode string using only characters in the range U+0000 to U+007F; a default character encoding
encoding; and optionally an isindex flag indicating that
the payload is to be processed as if it had been generated for a form containing an isindex control. The output of this algorithm is a sorted list
of name-value pairs. If the isindex flag is set and the first control really
was an isindex control, then the first name-value pair
will have as its name the empty string.
Which default character encoding to use can only be determined on a case-by-case basis, but
generally the best character encoding to use as a default is the one that was used to encode the
page on which the form used to create the payload was itself found. In the absence of a better
default, UTF-8 is suggested.
The isindex flag is for legacy use only. Forms in conforming HTML documents
will not generate payloads that need to be decoded with this flag set.
Let strings be the result of strictly splitting the string payload on U+0026 AMPERSAND
characters (&).
If the isindex flag is set and the first string in strings does not contain a U+003D EQUALS SIGN character (=), insert a U+003D
EQUALS SIGN character (=) at the start of the first string in strings.
Let pairs be an empty list of name-value pairs.
-
For each string string in strings, run these
substeps:
-
If string contains a U+003D EQUALS SIGN character (=), then let name be the substring of string from the start of string up to but excluding its first U+003D EQUALS SIGN character (=), and let
value be the substring from the first character, if any, after the first
U+003D EQUALS SIGN character (=) up to the end of string. If the first
U+003D EQUALS SIGN character (=) is the first character, then name will be
the empty string. If it is the last character, then value will be the
empty string.
Otherwise, string contains no U+003D EQUALS SIGN characters (=). Let
name have the value of string and let value be the empty string.
-
Replace any U+002B PLUS SIGN characters (+) in name and value with U+0020 SPACE characters.
-
Replace any escape in name and value with the
character represented by the escape. This replacement must not be recursive.
An escape is a U+0025 PERCENT SIGN character (%) followed by two ASCII hex
digits.
The character represented by an escape is the Unicode character whose code point is equal
to the value of the two characters after the U+0025 PERCENT SIGN character (%), interpreted as
a hexadecimal number (in the range 0..255).
So for instance the string "A%2BC" would become
"A+C". Similarly, the string "100%25AA%21" becomes
the string "100%AA!".
Convert the name and value strings to their byte
representation in ISO-8859-1 (i.e. convert the Unicode string to a byte string, mapping code
points to byte values directly).
Add a pair consisting of name and value to pairs.
If any of the name-value pairs in pairs have a name component
consisting of the string "_charset_" encoded in US-ASCII, and the value
component of the first such pair, when decoded as US-ASCII, is the name of a supported character
encoding, then let encoding be that character encoding (replacing the default
passed to the algorithm).
Convert the name and value components of each name-value pair in pairs
to Unicode by interpreting the bytes according to the encoding encoding.
Return pairs.
Parameters on the application/x-www-form-urlencoded MIME type are
ignored. In particular, this MIME type does not support the charset
parameter.
Multipart form data
The multipart/form-data encoding algorithm is as follows:
Let result be the empty string.
-
If the algorithm was invoked with an explicit character encoding, let the selected character
encoding be that encoding. (This algorithm is used by other specifications, which provide an
explicit character encoding to avoid the dependency on the form element described
in the next paragraph.)
Otherwise, if the form element has an accept-charset attribute, let the selected character
encoding be the result of picking an encoding for the form.
Otherwise, if the form element has no accept-charset attribute, but the document's
character encoding is an ASCII-compatible character encoding, then that is
the selected character encoding.
Otherwise, let the selected character encoding be UTF-8.
Let charset be the name of the
selected character encoding.
-
For each entry in the form data set, perform these substeps:
If the entry's name is "_charset_" and its
type is "hidden", replace its value with charset.
For each character in the entry's name and value that cannot be expressed using the
selected character encoding, replace the character by a string consisting of a U+0026 AMPERSAND
character (&), a U+0023 NUMBER SIGN character (#), one or more ASCII digits
representing the Unicode code point of the character in base ten, and finally a U+003B
SEMICOLON character (;).
-
Encode the (now mutated) form data set using the rules described by RFC 2388,
Returning Values from Forms: multipart/form-data, and return
the resulting byte stream. [[!RFC2388]]
Each entry in the form data set is a field, the name of the entry is the
field name and the value of the entry is the field value.
The order of parts must be the same as the order of fields in the form data set.
Multiple entries with the same name must be treated as distinct fields.
In particular, this means that multiple files submitted as part of a single
<input type=file multiple> element will result in each file
having its own field; the "sets of files" feature ("multipart/mixed") of RFC 2388
is not used.
The parts of the generated multipart/form-data resource that correspond to
non-file fields must not have a Content-Type header specified. Their names and
values must be encoded using the character encoding selected above (field names in particular do
not get converted to a 7-bit safe encoding as suggested in RFC 2388).
File names included in the generated multipart/form-data resource (as part of
file fields) must use the character encoding selected above, though the precise name may be
approximated if necessary (e.g. newlines could be removed from file names, quotes could be
changed to "%22", and characters not expressible in the selected character encoding could be
replaced by other characters). User agents must not use the RFC 2231 encoding suggested by RFC
2388.
The boundary used by the user agent in generating the return value of this algorithm is the
multipart/form-data boundary string. (This value is used to generate the
MIME type of the form submission payload generated by this algorithm.)
For details on how to interpret multipart/form-data payloads, see RFC 2388. [[!RFC2388]]
Plain text form data
The text/plain encoding algorithm is as follows:
Let result be the empty string.
-
If the form element has an accept-charset attribute, let the selected character
encoding be the result of picking an encoding for the form, with the allow
non-ASCII-compatible encodings flag unset.
Otherwise, if the form element has no accept-charset attribute, then that is the selected
character encoding.
Let charset be the name of the
selected character encoding.
If the entry's name is "_charset_" and its type
is "hidden", replace its value with charset.
If the entry's type is "file", replace its value with the file's
name only.
-
For each entry in the form data set, perform these substeps:
Append the entry's name to result.
Append a single U+003D EQUALS SIGN character (=) to result.
Append the entry's value to result.
Append a U+000D CARRIAGE RETURN (CR) U+000A LINE FEED (LF) character pair to result.
Encode result using the encoder for the selected
character encoding and return the resulting byte stream.
Payloads using the text/plain format are intended to be human readable. They are
not reliably interpretable by computer, as the format is ambiguous (for example, there is no way
to distinguish a literal newline in a value from the newline at the end of the value).