A form is a component of a Web page that has form controls, such as text, buttons, checkboxes,
range, or color picker controls. 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.
4.10.1.1 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 text
control. 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:
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:
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):
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:
The textarea element can be used to provide a multiline text control. In this
instance, we are going to use it to provide a space for the customer to give delivery
instructions:
4.10.1.2 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
4.10.1.3 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:
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 control blank, the user agent would submit the following to the online Web
service:
Support: form-validationChrome for Android56+Chrome10+UC Browser for Android11+iOS Safari (limited)4.0+Firefox4+IE10+Samsung Internet4+Opera Mini (limited)all+Android Browser4.4.3+Safari10.1+Edge12+Opera10.0+
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:
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:
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.
4.10.1.5 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:
4.10.1.6 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:
4.10.1.7 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, 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 text control (<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 text control.
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 romanized 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:
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.
4.10.1.8 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.
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.
Denotes elements that are listed in the form.elements and fieldset.elements APIs. These elements also
have a form content attribute, and a matching form IDL attribute, that allow authors to specify an explicit
form owner.
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.
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 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".
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 tree.
If there are multiple matching items, then a RadioNodeList object containing all
those elements is returned.
The elements IDL attribute must return an
HTMLFormControlsCollection rooted at the form 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.
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.
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.
If candidates is empty, let candidates be a liveRadioNodeList object containing all the img elements, whose form
owner is the form element, 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 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.
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 tree as the
label element. If the attribute is specified and there is an
element in the tree whose ID is equal to the value
of the for attribute, and the first such element in
tree order is a labelable element, then that
element is the label element's labeled control.
The label element's exact default presentation and behavior, in particular what
its activation behavior might be, if anything, should match the platform's label
behavior. The activation behavior 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 fire a click event at the input element, as if the
element itself had been triggered by the user:
Returns a NodeList of all the label elements that the form control
is associated with.
Labelable elements and all input elements
have a liveNodeList 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 and input elements, on getting,
must return that NodeList object, and that same value must always be returned, unless
this element is an input element whose type
attribute is in the Hidden state, in which case it
must instead return null.
This (non-conforming) example shows what happens to the NodeList and what labels returns when an input element has its type attribute changed.
<!doctype html>
<p><label><input></label></p>
<script>
const input = document.querySelector('input');
const labels = input.labels;
console.assert(labels.length === 1);
input.type = 'hidden';
console.assert(labels.length === 0); // the input is no longer the label's labeled control
console.assert(input.labels === null);
input.type = 'checkbox';
console.assert(labels.length === 1); // the input is once again the label's labeled control
console.assert(input.labels === labels); // same value as returned originally
</script>
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.
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, 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 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.
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.
If this element is not mutable, then abort these
steps.
If this element's type attribute is in the Checkbox state, then set this element's checkedness to its opposite value (i.e. true if it is false,
false if it is true) and set this element's indeterminate IDL attribute to false.
When an input element is first created, the element's rendering and behavior must
be set to the rendering and behavior 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.
When an input element's type attribute
changes state, the user agent must run the following steps:
If the previous state of the element's type attribute
put the value IDL attribute in the value mode, and the element's value is not the empty string, and the new state of the element's
type attribute puts the value IDL attribute in either the default mode or the default/on mode, then set the element's value content attribute to the element's value.
Otherwise, if the previous state of the element's type attribute put the value
IDL attribute in any mode other than the value mode, and the
new state of the element's type attribute puts the value IDL attribute in the value mode, then 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 set the control's dirty value
flag to false.
Otherwise, if the previous state of the element's type attribute put the value IDL attribute in any mode other than the filename mode, and the new state of the element's type attribute puts the value IDL attribute in the filename mode, then set the value of the element to the empty string.
Update the element's rendering and behavior to the new state's.
Signal a type change for the element. (The Radio Button state uses this, in particular.)
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 behavior.
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.
Support: indeterminate-checkboxChrome for Android56+Chrome28+UC Browser for AndroidNoneiOS SafariNoneFirefox3.6+IE6+Samsung Internet4+Opera MiniNoneAndroid Browser4.4+Safari6+Edge12+Opera11.6+
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 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.
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.
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 controls are distinguished from regular text controls, the Search state might result in an appearance consistent with
the platform's search controls rather than appearing like a regular text control.
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.
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.
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.
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 validabsolute URL, but may also or instead
automatically escape characters entered by the user so that the value is always a validabsolute 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.
<input type="url" name="location" list="urls">
<datalist id="urls">
<option label="MIME: Format of Internet Message Bodies" value="https://tools.ietf.org/html/rfc2045">
<option label="HTML" value="https://html.spec.whatwg.org/">
<option label="DOM" value="https://dom.spec.whatwg.org/">
<option label="Fullscreen" value="https://fullscreen.spec.whatwg.org/">
<option label="Media Session" value="https://mediasession.spec.whatwg.org/">
<option label="The Single UNIX Specification, Version 3" value="http://www.unix.org/version3/">
</datalist>
...and the user had typed "spec.w", and the user agent had also found that the user
had visited https://url.spec.whatwg.org/#url-parsing and https://streams.spec.whatwg.org/ 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.
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.
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.
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.
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.
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]
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.
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.
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.
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 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.
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 Date 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 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.
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.
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 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 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.
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 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).
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").
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.
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 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.
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 input element represents a control for setting the element's
value to a string representing a local date and time, with no time-zone offset
information.
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 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.
The algorithm to convert a string to a
number, given a string input, is as follows: If parsing a date and time from input results in an error, then return an error; otherwise, return the number of
milliseconds elapsed from midnight on the morning of 1970-01-01 (the time represented by the value
"1970-01-01T00:00:00.0") to the parsed local date and time, ignoring leap seconds.
The following example shows part of a flight booking application. The application uses an
input element with its type attribute set to
datetime-local, and it then interprets the
given date and time in the time zone of the selected airport.
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.
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.
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).
4.10.5.1.13 Range state (type=range)
Support: input-rangeChrome for Android56+Chrome4+UC Browser for Android11+iOS Safari5.0+Firefox23+IE10+Samsung Internet4+Opera MiniNoneAndroid Browser4.2+Safari3.1+Edge12+Opera9+
When an input element's type attribute is in
the Range 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, but with the
caveat that the exact value is not important, letting UAs provide a simpler interface than they
do for the Number state.
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:
Note how the UA determined the orientation of the control from the ratio of the
style-sheet-specified height and width properties. The colors 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:
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:
In this state, there is always a color 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 color represented by its value, as
obtained from applying the rules for parsing simple color values to it. User agents
must not allow the user to set the value to a string that is
not a valid lowercase simple color. If the user agent provides a user interface for
selecting a color, then the value must be set to the result
of using the rules for serializing simple color values to the user's selection. User
agents must not allow the user to set the value to the empty
string.
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.
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.
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.
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:
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:
The element's checkedness state is set to true (for
whatever reason).
The element's name attribute is set, changed, or
removed.
If the user tries to submit this form without first selecting "Doggo", then bothinput elements will be suffering from being missing, since an element
in the radio button group is required
(viz. the first element), and both of the elements in the radio button group have a false checkedness.
On the other hand, if the user selects "Doggo" and then submits the form, then neither
input element will be suffering from being missing, since while one of
them is required, not all of them have a false checkedness.
If none of the radio buttons in a radio button group are checked,
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.
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.
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.
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 an
event named input at the input element, with
the bubbles attribute initialized to true, and finally
fire an event named change at the input element, with the bubbles attribute initialized to true.
If the element is not mutable, the user agent must not allow
the user to change the element's selection.
The accept attribute may be specified to
provide user agents with a hint of what file types will be accepted.
Support: input-file-acceptChrome for Android (limited)56+Chrome26+UC Browser for AndroidNoneiOS Safari (limited)8+Firefox37+IE10+Samsung Internet (limited)4+Opera MiniNoneAndroid BrowserNoneSafari (limited)6+EdgeNoneOpera15+
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:
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>
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.
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 these events occur
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
then unless the user agent cannot support images, or its support for images has been disabled,
or the user agent only fetches images on demand, or the src
attribute's value is the empty string, the user agent must parse the value of the src
attribute value, relative to the element's node document, and if that is successful,
run these substeps:
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.
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 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.
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 input
activation behavior 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.
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.
Many aspects of this state's behavior are similar to the behavior of the
img element. Readers are encouraged to read that section, where many of the same
requirements are described in more detail.
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.)
4.10.5.1.20 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.
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 behavior. 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.
4.10.5.2 Implementation 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...)
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.
Support: maxlengthChrome for Android56+Chrome4+UC Browser for Android (limited)11+iOS Safari9.0+Firefox4+IE10+Samsung Internet4+Opera Mini (limited)all+Android Browser2.3+Safari5.1+Edge12+Opera15+
The following extract shows how a messaging client's text entry could be arbitrarily
restricted to a fixed number of characters, thus forcing any conversation through this medium to
be terse and discouraging intelligent discourse.
<label>What are you doing? <input name=status maxlength=140></label>
The size attribute gives the number of
characters that, in a visual rendering, the user agent is to allow the user to see while editing
the element's value.
If the attribute is present, then its value must be parsed using the rules for parsing
non-negative integers, and if the result is a number greater than zero, then the user agent
should ensure that at least that many characters are visible.
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.
Support: readonly-attrChrome for Android56+Chrome26+UC Browser for Android11+iOS Safari7.0+Firefox4+IE6+Samsung Internet4+Opera Miniall+Android Browser2.3+Safari5.1+Edge12+Opera15+
The difference between disabled and readonly is that read-only controls can still function,
whereas disabled controls generally do not function as controls until they are enabled. This is
spelled out in more detail elsewhere in this specification with normative requirements that refer
to the disabled concept (for example, the element's
activation behavior, whether or not it is a focusable area, or when
constructing the form data set). Any other behavior related to user interaction with
disabled controls, such as whether text can be selected or copied, is not defined in this
specification.
Only text controls can be made read-only, since for other controls (such as checkboxes and
buttons) there is no useful distinction between being read-only and being disabled, so the
readonly attribute does not
apply.
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).
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.
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.
If the user had, amongst many friends in their user contacts database, two friends
"Spider-Man" (with address "spider@parker.example.net") and "Scarlet Witch" (with address
"scarlet@avengers.example.net"), then, after the user has typed "s", 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:
Suppose the user had entered "bob@example.net" into this text control, and then
started typing a second e-mail address starting with "s". 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.
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.
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. [JAVASCRIPT]
If the value doesn't compile successfully, user agents are encouraged to log this
fact in a developer console, to aid debugging.
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.
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.
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.
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.
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 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 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.
If a default step base is defined for
this element given its type attribute's state, then return
it and abort these steps.
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 tree.
The suggestions source element is the first element in
the tree 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. If appropriate, the user agent should use the suggestion's
label and value to identify the suggestion to the user.
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. If filtering
based on the user's input, user agents should use substring matching against both the suggestions'
label and value.
This text field allows you to choose a type of JavaScript function.
For user agents that follow the above suggestions, both the label and value
would be shown:
Then, typing "arrow" or "=>" would filter the list to the entries with
labels "arrow function" and "async arrow function". Typing "generator" or
"*" would filter the list to the entries with labels "generator function" and "async
generator function".
As always, user agents are free to make user interface decisions which are
appropriate for their particular requirements and for the user's particular circumstances. However,
this has historically been an area of confusion for implementers, web developers, and users alike,
so we've given some "should" suggestions above.
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:
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 themself.
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 themself added
an entry with that value, or edited an existing entry to be that value. Which behavior is to be
applied depends on the user interface in a user-agent-defined manner.
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.
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.
Support: input-placeholderChrome for Android56+Chrome4+UC Browser for Android11+iOS Safari3.2+Firefox4+IE10+Samsung Internet4+Opera Miniall+Android Browser4.2+Safari5+Edge12+Opera11.5+
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, after having stripped newlines 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:
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:
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 behavior:
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 control, 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"DOMException.
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 setting, if the valueAsDate attribute does not apply, as defined for the input element's type attribute's current state, then throw an
"InvalidStateError"DOMException; otherwise, if the new
value is not null and not a Date object throw a TypeError 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, 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"DOMException. Otherwise, if the new
value is a Not-a-Number (NaN) value, then set the value of
the element to the empty 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 stepDown(n) and stepUp(n) methods, when invoked,
must run the following algorithm:
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.
Let valueBeforeStepping be value.
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() method, 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:
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.
If either the method invoked was the stepDown()
method and value is greater than valueBeforeStepping, or the method
invoked was the stepUp() method and value is
less than valueBeforeStepping, then abort these steps.
This ensures that invoking the stepUp() method on the
input element in the following example does not change the value of that element:
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 input activation behavior, 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 input activation behavior, 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 an event named input at the input element, with the bubbles attribute initialized to true, and any time the user
commits the change, the user agent must queue a task to fire an event named change
at the input element, with the bubbles
attribute initialized to true.
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 input activation behavior, 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 an
event named input at the input element, with
the bubbles attribute initialized to true, and then fire an event named change
at the input element, with the bubbles
attribute initialized to true.
An example of a user interface with a commit action would be a Color control that consists of a single button that brings
up a color 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 color 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 input activation behavior, 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 an
event named input at the input element, with
the bubbles attribute initialized to true. 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 control, pasting
a new value into the control, or undoing an edit in that control. Some user interactions do not
cause changes to the value, e.g., hitting the "delete" key in an empty text control, or replacing
some text in the control 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 an
event named input at the input element, with
the bubbles attribute initialized to true, then fire an event named change
at the input element, with the bubbles
attribute initialized to true.
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 type attribute controls the behavior 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.
A button element's activation behavior is to run the steps defined in
the following list for the current state of this element's type attribute, if this element is not disabled, and do nothing otherwise:
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.
The value IDL attribute must
reflect the content attribute of the same name.
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.
In practice, the requirement stated in the paragraph above can only apply when a
select element does not have a size attribute
with a value greater than 1.
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 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 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.
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 behavior.
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.
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 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.
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.
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.
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 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.
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 they 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>
4.10.8 The datalist element
Support: datalistChrome for Android56+Chrome (limited)20+UC Browser for Android11+Firefox (limited)4+IE (limited)10+Samsung Internet4+Opera MiniNoneAndroid Browser4.4.3+Edge (limited)12+Opera (limited)15+
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.
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.
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.
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 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>
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.
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.
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 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.
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.
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 behavior 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, the constructor must
perform the following steps:
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.
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 control 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>
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 an event named input at the textarea element, with the bubbles attribute initialized to true. 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.
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.
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 normalized 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, textLength IDL attribute, and by the
maxlength and minlength content attributes. It is normalized 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 normalized 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.
Replace every U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair with a single
U+000A LINE FEED (LF) character.
Replace every remaining U+000D CARRIAGE RETURN character 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 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 behavior.
The type IDL attribute must return the value
"textarea".
The defaultValue IDL attribute must
act like the element's textContent IDL attribute.
The value IDL 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 control, unselecting
any selected text and resetting the selection direction to none.
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 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 tree.
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 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 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 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:
(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.
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 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.
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:
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.
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.
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.
Support: fieldset-disabledChrome for Android56+Chrome20+UC Browser for Android11+iOS Safari6.0+Firefox4+IE (limited)6+Samsung Internet4+Opera Mini (limited)all+Android Browser4.4+Safari6+Edge12+Opera10.0+
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.
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 controls
and an optional year/month control.
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.
Returns the element's form element, if any, or null otherwise.
The form IDL attribute's behavior depends on
whether the legend element is in a fieldset element or not. If the
legend has a fieldset element as its parent, then the form IDL attribute must return the same value as the form IDL attribute on that fieldset element. Otherwise,
it must return null.
4.10.17 Form control infrastructure
4.10.17.1 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. Or, if a user enters the email address " awesome@example.com"
(with leading whitespace) into an email field, the
user's input would be the string " awesome@example.com" but the browser's UI for
email fields might translate that into a value of "awesome@example.com" (without the leading whitespace).
To define the behavior of constraint validation in the face of the input
element's multiple attribute, input elements
can also have separately defined values.
To define the behavior of the maxlength and minlength attributes, as well as other APIs specific to the
textarea element, all form control with a value also have an algorithm for obtaining an API value. By
default this algorithm is to simply return the control's value.
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.
A form-associated element is, by default, associated with its nearest ancestor form element (as described
below), but, if it is listed, may have a form attribute specified to override this.
Support: form-attributeChrome for Android56+Chrome10+UC Browser for Android11+iOS Safari5.0+Firefox4+IENoneSamsung Internet4+Opera Miniall+Android Browser3+Safari5.1+EdgeNoneOpera9.5+
The rules in this section are complicated by the fact that although conforming
documents or trees will never contain nested form
elements, it is quite possible (e.g., using a script that performs DOM manipulation) to generate
trees 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.
If element is listed, has a form content attribute, and is connected, then run
this substep:
If the first element in element's tree, in tree
order, to have an ID that is case-sensitively equal to element's form content attribute's value, is a form element,
then associate the element with that
form element.
Otherwise, if element has an ancestor form element, then associateelement with the nearest such
ancestor form element.
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, and there is a parse error for the </form> tag.
4.10.18.1 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 or isindex.
A number of user agents historically implemented special support for first-in-form
text controls with the name isindex, and this specification previously
defined related user agent requirements for it. However, some user agents subsequently dropped
that special support, and the related requirements were removed from this specification. So, to
avoid problematic reinterpretations in legacy user agents, the name isindex
is no longer allowed.
Other than isindex, any non-empty value for name is allowed. The name _charset_ is special: if used as the name of a Hidden control with no value attribute, then during submission the value attribute is automatically given a value consisting of the
submission character encoding.
The name IDL attribute must reflect
the name content attribute.
4.10.18.2 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 control 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 control and a submission button:
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:
4.10.18.3 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. The "number of characters" is measured using code-unit length and,
in the case of textarea elements, with all line breaks normalized to a single
character (as opposed to CRLF pairs).
4.10.18.4 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 "number of characters" is measured using code-unit
length and, in the case of textarea elements, with all line breaks normalized
to a single character (as opposed to CRLF pairs).
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.
In this example, there are four text controls. 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>
4.10.18.5 Enabling and disabling form controls: the disabled attribute
A form control is disabled if any of the following
conditions are met:
The element is a button, input, select, or
textarea element, and the disabled attribute
is specified on this element (regardless of its value).
The element is a descendant of a fieldset element whose disabled attribute is specified, and is not a
descendant of that fieldset element's first legend element child, if
any.
The disabled IDL attribute must
reflect the disabled content attribute.
4.10.18.6 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).
Support: form-submit-attributesChrome for Android56+Chrome15+UC Browser for Android11+iOS Safari5.0+Firefox4+IE10+Samsung Internet4+Opera Miniall+Android Browser4+Safari5.1+Edge12+Opera10.6+
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 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:
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 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 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.
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 element's node
document's URL 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 element's node document's URL 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.
4.10.18.6.1 Autofocusing a form control: the autofocus attribute
Support: autofocusChrome for Android56+Chrome5+UC Browser for AndroidNoneiOS SafariNoneFirefox4+IE10+Samsung Internet4+Opera MiniNoneAndroid Browser3+Safari5+Edge12+Opera9.5+
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.
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 last inclusive ancestor
element.
If the user has indicated (for example, by starting to type in a form control) that they
do 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 has to 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.
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 recognize 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 behavior 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.
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-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-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.
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 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.
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>".)
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.
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.
Text input in the user's locale, with keys for aiding in the input of URLs, 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.
4.10.18.8 Autofill
Support: input-autocomplete-onoffChrome for Android56+Chrome (limited)27+UC Browser for Android11+iOS Safari5.0+Firefox (limited)30+IE (limited)11+Samsung Internet4+Opera Miniall+Android Browser2.1+Safari (limited)7+Edge (limited)12+Opera9+
4.10.18.8.1 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.
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: <textarea name=ba autocomplete="section-blue shipping street-address"></textarea> </label>
<p> <label> City: <input name=bc autocomplete="section-blue shipping address-level2"> </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: <textarea name=ra autocomplete="section-red shipping street-address"></textarea> </label>
<p> <label> City: <input name=rc autocomplete="section-red shipping address-level2"> </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
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 them; 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.
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.
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
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
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
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)
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).
4.10.18.8.2 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 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.
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 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:
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:
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.
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 its tree,
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 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:
The only value that a conforming user agent could suggest in the text control 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 must not discriminate between form controls that are
in a document tree and those that are connected; that is, it is not
conforming to make the decision on whether or not to autofill based on whether the element's
root is a shadow root versus a Document.
...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. (Note that this example is non-conforming, because the autofill
field namebday is not allowed with the
Month state.)
The user agent picks the month from the listed options, either by noticing there are twelve
options and picking the 7th, or by recognizing 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.
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.
4.10.19 APIs for the text control selections
The input and textarea elements define several attributes and methods
for handling their selection. Their shared algorithms are defined here.
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:
Attempts to preserve the selection. This is the default.
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, when invoked,
must run the following steps:
If this element is an input element, and either select()does not
apply to this element or the corresponding control has no selectable text, return.
For instance, in a user agent where <input type=color> is rendered as a color well with a
picker, as opposed to a text control accepting a hexadecimal color code, there would be no
selectable text, and thus calls to the method are ignored.
To set the selection range with an integer or null start, an integer or
null or the special value infinity end, and optionally a string direction,
run the following steps:
If start is null, let start be zero.
If end is null, let end be zero.
Set the selection of the text control 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 control (including the special value infinity) must be treated as pointing
at the end of the text control. 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).
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 the length of the value of the text control, then set
it to the length of the value of the text control.
If end is greater than the length of the value of the text control, then set it
to the length of the value of the text control.
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 control,
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.)
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);
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.)
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.
4.10.20.2 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:
If notCanceled is true, 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.
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.
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.
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's getter must return a
ValidityState object that represents the validity states of this
element. This object is live.
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.
If report is true, then report the problems with the constraints of this
element to the user. When reporting the problem with the constraints to the user, the user
agent may run the focusing steps for this element, and may change the scrolling
position of the document, or perform some other action that brings this element to the user's
attention. User agents may report more than one constraint violation, if this element suffers
from multiple problems at once. If this element is not being rendered, then the
user agent may, instead of notifying the user, report the error for the
running script.
Return false.
Return true.
The validationMessage attribute's
getter must run these steps:
Return a suitably localized 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
return a suitably localized 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.
4.10.20.4 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.
4.10.21 Form submission
4.10.21.1 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.
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.
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:
If the user agent supports letting the user submit a form implicitly (for example, on some
platforms hitting the "enter" key while a text control is focused implicitly submits
the form), then doing so for a form, whose default button has activation
behavior and is not disabled, must cause the user
agent to fire a click event at that default
button.
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.
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 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 an event named
invalid at the form element and then abort these
steps.
If the submitted from submit() method flag
is not set, then:
Let continue be the result of firing an
event named submit at form, with the
bubbles attribute initialized to true and the cancelable attribute initialized to true.
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.
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 behavior 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 behaviors described below, when the
user agent is required to plan to navigate to a particular resource destination, it must run the following steps:
Navigatetarget browsing context to
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.
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 dialogsubject. If there is a result, let that be the return value.
4.10.21.4 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.
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.
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.
Replace the name of each entry in the form data set, and the value of each
entry in the form data set whose type is not "file", with the
results of converting to a sequence of Unicode scalar values.
Return the form data set.
4.10.21.5 Selecting a form submission encoding
If the user agent is to pick an encoding for a
form, it must run the following steps:
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.
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 7578,
Returning Values from Forms: multipart/form-data, and return
the resulting byte stream. [RFC7578]
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.
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.
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).
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 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.
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.
Return result.
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).
4.10.22 Resetting a form
When a form element form is reset, run these steps:
Each resettable element defines its own reset algorithm. Changes made to form controls as part of
these algorithms do not count as changes caused by the user (and thus, e.g., do not cause input events to fire).
Support: detailsChrome for Android56+Chrome12+UC Browser for Android11+iOS Safari6.0+Firefox49+IENoneSamsung Internet4+Android Browser4+Safari6+EdgeNoneOpera15+
The details element represents a disclosure widget from which the
user can obtain additional information or controls.
The details element is not appropriate for footnotes. Please see the section on footnotes for details on how to mark up footnotes.
The first summary element child of the element, if any,
represents the summary or legend of the details. If there is no
child summary element, the user agent should provide its own legend (e.g.
"Details").
The rest of the element's contents represents the additional information or
controls.
The open content attribute is a boolean
attribute. If present, it indicates that both the summary and the additional information is
to be shown to the user. If the attribute is absent, only the summary is to be shown.
When the element is created, if the attribute is absent, the additional information should be
hidden; if the attribute is present, that information should be shown. Subsequently, if the
attribute is removed, then the information should be hidden; if the attribute is added, the
information should be shown.
The user agent should allow the user to request that the additional information be shown or
hidden. To honor a request for the details to be shown, the user agent must set the open attribute on the element to the empty string. To honor a
request for the information to be hidden, the user agent must remove the open attribute from the element.
This ability to request that additional information be shown or hidden
may simply be the activation behavior of the appropriate
summary element, in the case such an element exists. However, if no such element
exists, user agents can still provide this ability through some other user interface
affordance.
Whenever the open attribute is added to or removed from
a details element, the user agent must queue a task that runs the
following steps, which are known as the details notification task steps, for this
details element:
One could use this in conjunction with other details in a list to allow the user
to collapse a set of fields down to a small set of headings, with the ability to open each
one.
In these examples, the summary really just summarizes what the controls can change, and not
the actual values, which is less than ideal.
Because the open attribute is added and removed
automatically as the user interacts with the control, it can be used in CSS to style the element
differently based on its state. Here, a stylesheet is used to animate the color of the summary
when the element is opened or closed:
If the element's type attribute is in the context menu state: in any order, zero or more menuitem elements, zero or more hr elements, zero or more menu elements whose type attributes are in the context menu state, and zero or more script-supporting elements.
The type attribute is an enumerated
attribute indicating the kind of menu being declared. The attribute has two states. The
"context" keyword maps to the context menu state, in which the element is declaring a context
menu. The "toolbar" keyword maps to the
toolbar state, in which the element is declaring a toolbar. The
attribute may also be omitted. The missing value default is
the context menu state if the parent element is a
menu element whose type attribute is in the
context menu state; otherwise, it is the toolbar state.
If a menu element's type attribute is in the
context menu state, then the element
represents the commands of a context menu, and the user can only examine and interact
with the commands if that context menu is activated through some other element via the contextmenu attribute.
If a menu element's type attribute is in the
toolbar state, then the element represents a
toolbar consisting of its contents, in the form of either an unordered list of items (represented
by li elements), each of which represents a command that the user can perform or
activate, or, if the element has no li element children, flow content
describing available commands.
These two states are very different. The toolbar state is simply a
semantic alternative to ul to express an unordered list of commands (a "toolbar").
The context menu state, in combination with the contextmenu global attribute, can be used to customize the
contextual menus of user agents as explained in the processing model section below.
The label attribute gives the label of the
menu. It is used by user agents to display nested menus in the UI: a context menu containing
another menu would use the nested menu's label attribute for
the submenu's menu label. The label attribute must only be
specified on menu elements whose parent element is a menu element whose
type attribute is in the context menu state.
The type attribute indicates the kind of
command: either a normal command with an associated action, or a state or option that can be
toggled, or a selection of one item from a list of items.
The element represents a normal command with an associated action.
The Checkbox state
The element represents a state or option that can be toggled.
The Radio state
The element represents a selection of one item from a list of items.
The label attribute gives the name of the
command, as shown to the user. If the label attribute is
specified, it must have a value that is not the empty string.
The icon attribute gives a picture that
represents the command. If the attribute is specified, the attribute's value must contain a
valid non-empty URL potentially surrounded by spaces. To obtain
the absolute URL of the icon when the attribute's value is not the empty string, the
attribute's value must be parsed relative to the element's
node document. When the attribute is absent, or its value is the empty string, or
parsing its value fails, there is no icon.
The disabled attribute is a
boolean attribute that, if present, indicates that the command is not available in
the current state.
The distinction between disabled and
hidden is subtle. A command would be disabled if, in the same
context, it could be enabled if only certain aspects of the situation were changed. A command
would be marked as hidden if, in that situation, the command will never be enabled. For example,
in the context menu for a water faucet, the command "open" might be disabled if the faucet is
already open, but the command "eat" would be marked hidden since the faucet could never be
eaten.
The checked attribute is a boolean
attribute that, if present, indicates that the command is selected. The attribute must be
omitted unless the type attribute is in either the Checkbox state or the Radio state.
The radiogroup attribute gives the
name of the group of commands that will be toggled when the command itself is toggled, for
commands whose type attribute has the value "radio". The scope of the name is the child list of the parent element. The
attribute must be omitted unless the type attribute is in
the Radio state. When specified, the
attribute's value must be a non-empty string.
The title attribute gives a hint describing
the command, which might be shown to the user to help them.
The default attribute indicates, if
present, that the command is the one that would have been invoked if the user had directly
activated the menu's subject instead of using the menu. The default attribute is a boolean 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 icon, disabled, checked, and radiogroup, and default IDL attributes must reflect the
respective content attributes of the same name.
The element's activation behavior is to run the steps defined in the following
list for the current state of this type attribute, if
this element's Disabled State is false
(enabled), and do nothing otherwse:
If the element has a checked attribute, the UA
must remove that attribute. Otherwise, the UA must add a checked attribute, with the literal value "checked".
If the element has a parent, then the UA must walk the list of child nodes of that parent
element, and for each node that is a menuitem element, if that element has a radiogroup attribute whose value exactly matches the
current element's (treating missing radiogroup
attributes as if they were the empty string), and has a checked attribute, must remove that attribute.
Then, the element's checked attribute must be set
to the literal value "checked".
The contextmenu attribute gives the element's
context menu. The value must be the ID of a menu
element in the same tree whose type attribute is
in the context menu state.
When a user right-clicks on an element with a contextmenu attribute, the user agent will first fire a contextmenu event at the element, and then, if that event is not
canceled, a show event at the menu element.
Here is an example of a context menu for an input control:
<form name="npc">
<label>Character name: <input name=char type=text contextmenu=namemenu required></label>
<menu type=context id=namemenu>
<menuitem onclick="document.forms.npc.elements.char.value = getRandomName()">
Pick random name
</menuitem>
<menuitem onclick="prefillFields(document.forms.npc.elements.char.value)">
Prefill other fields based on name
</menuitem>
</menu>
</form>
This adds two items to the control's context menu, one called "Pick random name", and one
called "Prefill other fields based on name". They invoke scripts that are not shown in the
example above.
When an element's context menu is requested (e.g. by the user right-clicking the element, or
pressing a context menu key), the user agent must apply the appropriate rules from the following
list:
If the user requested a context menu using a pointing device
The user agent must fire an event named contextmenu at the element for which the menu was requested,
using MouseEvent, with the bubbles and cancelable attributes initialized to true, and other
attributes initialized to the same values as the last MouseEvent user interaction
event that was fired as part of the gesture that was interpreted as a request for the context
menu.
Typically, therefore, the firing of the contextmenu event will be the default action of a mouseup or keyup event. The exact
sequence of events is UA-dependent, as it will vary based on platform conventions.
The default action of the contextmenu event depends on
whether or not the element for which the menu was requested has a non-null assigned context
menu when the event dispatch has completed, as follows.
If the assigned context menu of the element for which the menu was requested is
null, the default action must be for the user agent to show its default context menu, if it has
one.
Otherwise, let subject be the element for which the menu was requested, and let
menu be the assigned context menu of target immediately after
the contextmenu event's dispatch has completed. The user
agent must run these steps:
If build is true, then build and
show the context menu for menu with subject as the subject.
The user agent may also provide access to its default context menu, if any, with the context
menu shown. For example, it could merge the menu items from the two menus together, or provide the
page's context menu as a submenu of the default menu. In general, user agents are encouraged to
de-emphasize their own contextual menu items, so as to give the author's context menu the
appearance of legitimacy — to allow documents to feel like "applications" rather than "mere
Web pages".
In this example, an image of cats is given a context menu with four possible commands:
<img src="cats.jpeg" alt="Cats" contextmenu=catsmenu>
<menu type="context" id="catsmenu">
<menuitem label="Pet the kittens" onclick="kittens.pet()"></menuitem>
<menuitem label="Cuddle with the kittens" onclick="kittens.cuddle()"></menuitem>
<menu label="Feed the kittens">
<menuitem label="Fish" onclick="kittens.feed(fish)"></menuitem>
<menuitem label="Chicken" onclick="kittens.feed(chicken)"></menuitem>
</menu>
</menu>
When a user of a mouse-operated visual Web browser right-clicks on the image, the browser
might pop up a context menu like this:
When the user clicks the disclosure triangle, such a user agent would expand the context menu
in place, to show the browser's own commands:
User agents may provide means for bypassing the context menu processing model, ensuring that
the user can always access the UA's default context menus. For example, the user agent could
handle right-clicks that have the Shift key depressed in such a way that it does not fire the
contextmenu event and instead always shows the default
context menu.
A context menu construct consists of an ordered list of zero or
more context menu item
constructs, which can be any of:
Other context menu constructs, each with an associated
submenu label, which allows the list to be nested (menu)
To build and show a context menu for a particular
menu element source and with a particular element subject as a
subject, the user agent must run the following steps:
The context menu item generator steps for a menu element using a
specific context menu constructoutput as output are as follows: For
each child node of the menu in tree order, run the appropriate steps
from the following list:
Returns the other event target involved in this event. For example, when a show event fires on a menu element, the other event
target involved in the event would be the element for which the menu is being shown.
The relatedTarget attribute
must return the value it was initialized to. It represents the other event target that is related
to the event.
4.11.6 Commands
4.11.6.1 Facets
A command is the abstraction behind menu items, buttons, and
links. Once a command is defined, other parts of the interface can refer to the same command,
allowing many access points to a single feature to share facets such as the Disabled State.
Commands are defined to have the following facets:
Label
The name of the command as seen by the user.
Access Key
A key combination selected by the user agent that triggers the command. A command might not
have an Access Key.
Hidden State
Whether the command is hidden or not (basically, whether it should be shown in menus).
Disabled State
Whether the command is relevant and can be triggered or not.
Action
The actual effect that triggering the command will have. This could be a scripted event
handler, a URL to which to navigate, or a form submission.
User agents may expose the commands that match the following criteria:
The Disabled State of the command is true if
the element or one of its ancestors is inert, or if the element's disabled state is set, and false otherwise.
4.11.6.4 Using the input element to define a command
The Label of the command is determined as
follows:
If the type attribute is in one of the
Submit Button, Reset Button, Image
Button, or Button states, then the
Label is the string given by the
value attribute, if any, and a UA-dependent,
locale-dependent value that the UA uses to label the button itself if the attribute is
absent.
Otherwise, if the element is a labeled control, then the
Label is the string given by the
textContent of the first label element in tree order
whose labeled control is the element in question. (In DOM terms, this is the
string given by element.labels[0].textContent.)
Otherwise, if the value attribute is present, then
the Label is the value of that attribute.
The Hidden State of the command is true (hidden)
if the element has a hidden attribute, and false otherwise.
The Disabled State of the command is true if
the element or one of its ancestors is inert, or if the element's disabled state is set, and false otherwise.
The Hidden State of the command is true (hidden)
if the element has a hidden attribute, and false otherwise.
The Disabled State of the command is true if
the element is disabled, or if its nearest ancestor
select element is disabled, or if it or one
of its ancestors is inert, and false otherwise.
The Hidden State of the command is true (hidden)
if the element has a hidden attribute, and false otherwise.
The Disabled State of the command is true if
the element or one of its ancestors is inert, or if the element has a disabled attribute, and false otherwise.
If one of the earlier sections that define elements that define
commands define that this element defines a command,
then that section applies to this element, and this section does not. Otherwise, this section
applies to that element.
The Label of the command depends on the element. If
the element is a labeled control, the textContent of the first
label element in tree order whose labeled control is the
element in question is the Label (in DOM terms, this is
the string given by element.labels[0].textContent). Otherwise,
the Label is the textContent of the element
itself.
The dialog element represents a part of an application that a user interacts with
to perform a task, for example a dialog box, inspector, or window.
The open attribute is a boolean
attribute. When specified, it indicates that the dialog element is active and
that the user can interact with it.
A dialog element without an open attribute
specified should not be shown to the user. This requirement may be implemented indirectly through
the style layer. For example, user agents that support the suggested
default rendering implement this requirement using the CSS rules described in the rendering section.
Removing the open attribute will usually hide the
dialog. However, doing so has a number of strange additional consequences:
For these reasons, it is generally better to never remove the open attribute manually. Instead, use the close() method to close the dialog, or the hidden attribute to hide it.
The tabindex attribute must not be specified on
dialog elements.
Each Document has a stack of dialog elements known as the
pending dialog stack. When a Document is created, this stack must be
initialized to be empty.
When the close() method is invoked, the user
agent must close the dialog that the method was invoked on. If the method was invoked
with an argument, that argument must be used as the return value; otherwise, there is no return
value.
When a dialog element subject is to be closed, optionally with a return value result, the user agent
must run the following steps:
If subject does not have an open
attribute, then abort these steps.
The returnValue IDL attribute, on
getting, must return the last value to which it was set. On setting, it must be set to the new
value. When the element is created, it must be set to the empty string.
Canceling dialogs: When a Document's
pending dialog stack is not empty, user agents may provide a user interface that,
upon activation, queues a task to run these steps:
If close is true and dialog has an open attribute, then close the dialog with no
return value.
An example of such a UI mechanism would be the user pressing the "Escape" key.
A dialog element is in one of two modes: normal alignment or
centered alignment. When a dialog element is created, it must be placed in
the normal alignment mode. In this mode, normal CSS requirements apply to the
element. The centered alignment mode is only used for dialog elements
that are in the top layer. [FULLSCREEN][CSS]
When an element subject is placed in centered alignment mode,
and when it is in that mode and has new rendering boxes created, the user agent must set up the
element such that its top static position, for the purposes of calculating the
used value of the 'top' property, is the value that would place the
element's top margin edge as far from the top of the viewport as the
element's bottom margin edge from the bottom of the viewport, if the
element's height is less than the height of the viewport, and otherwise is the value
that would place the element's top margin edge at the top of the
viewport.
This top static position of a dialog element with centered alignment
must remain the element's top static position until its boxes are recreated. (The element's static
position is only used in calculating the used value of the 'top'
property in certain situations; it's not used, for instance, to position the element if its
'position' property is set to 'static'.)
User agents in visual interactive media should allow the user to pan the viewport
to access all parts of a dialog element's border box, even if the
element is larger than the viewport and the viewport would otherwise not
have a scroll mechanism (e.g. because the viewport's 'overflow' property
is set to 'hidden').
The open IDL attribute must
reflect the open content attribute.
This dialog box has some small print. The main element is used to draw the user's
attention to the more important parts.
<dialog>
<h1>Add to Wallet</h1>
<main>
<p>How many gold coins do you want to add to your wallet?</p>
<p><input name=amt type=number min=0 step=0.01 value=100></p>
</main>
<p><small>You add coins at your own risk.</small></p>
<p><label><input name=round type=checkbox> Only add perfectly round coins </label>
<p><input type=button onclick="submit()" value="Add Coins"></p>
</dialog>
