4.10.19 Attributes common to form controls

4.10.19.1 Naming form controls

The name content attribute gives the name of the form control, as used in form submission and in the form element's elements object. If the attribute is specified, its value must not be the empty string.

Any non-empty value for name is allowed, but the names "_charset_" and "isindex" are special:

isindex

This value, if used as the name of a Text control that is the first control in a form that is submitted using the application/x-www-form-urlencoded mechanism, causes the submission to only include the value of this control, with no name.

_charset_

This value, if used as the name of a Hidden control with no value attribute, is automatically given a value during submission consisting of the submission character encoding.

The name IDL attribute must reflect the name content attribute.

4.10.19.2 Enabling and disabling form controls

The disabled content attribute is a boolean attribute.

A form control is disabled if its disabled attribute is set, or if it is a descendant of a fieldset element whose disabled attribute is set and is not a descendant of that fieldset element's first legend element child, if any.

A form control that is disabled must prevent any click events that are queued on the user interaction task source from being dispatched on the element.

Constraint validation: If an element is disabled, it is barred from constraint validation.

The disabled IDL attribute must reflect the disabled content attribute.

4.10.19.3 A form control's value

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.

To define the behaviour of constraint validation in the face of the input element's multiple attribute, input elements can also have separately defined values.

4.10.19.4 Autofocusing a form control

The autofocus content attribute allows the author to indicate that a control is to be focused as soon as the page is loaded, allowing the user to just start typing without having to manually focus the main control.

The autofocus attribute is a boolean attribute.

There must not be more than one element in the document with the autofocus attribute specified.

When an element with the autofocus attribute specified is inserted into a document, user agents should run the following steps:

  1. Let target be the element's Document.

  2. If target has no browsing context, abort these steps.

  3. If target's browsing context has no top-level browsing context (e.g. it is a nested browsing context with no parent browsing context), abort these steps.

  4. If target's browsing context had the sandboxed automatic features browsing context flag set when target was created, abort these steps.

  5. If target's origin is not the same as the origin of the Document of the currently focused element in target's top-level browsing context, abort these steps.

  6. If target's origin is not the same as the origin of the active document of target's top-level browsing context, abort these steps.

  7. If the user agent has already reached the last step of this list of steps in response to an element being inserted into a Document whose top-level browsing context's active document is the same as target's top-level browsing context's active document, abort these steps.

  8. If the user has indicated (for example, by starting to type in a form control) that he does not wish focus to be changed, then optionally abort these steps.

  9. Queue a task that checks to see if the element is focusable, and if so, runs the focusing steps for that 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 DOM manipulation task source.

Focusing the control does not imply that the user agent must focus the browser window if it has lost focus.

The autofocus IDL attribute must reflect the content attribute of the same name.

In the following snippet, the text control would be focused when the document was loaded.

<input maxlength="256" name="q" value="" autofocus>
<input type="submit" value="Search">
4.10.19.5 Limiting user input length

A form control maxlength attribute, controlled by a dirty value flag, declares a limit on the number of characters a user can input.

If an element has its form control maxlength attribute specified, the attribute's value must be a valid non-negative integer. If the attribute is specified and applying the rules for parsing non-negative integers to its value results in a number, then that number is the element's maximum allowed value length. If the attribute is omitted or parsing its value results in an error, then there is no maximum allowed value length.

Constraint validation: If an element has a maximum allowed value length, its dirty value flag is true, its value was last changed by a user edit (as opposed to a change made by a script), and the code-point length of the element's value is greater than the element's maximum allowed value length, then the element is suffering from being too long.

User agents may prevent the user from causing the element's value to be set to a value whose code-point length is greater than the element's maximum allowed value length.

4.10.19.6 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).

The attributes for form submission that may be specified on form elements are action, enctype, method, novalidate, and target.

The corresponding attributes for form submission that may be specified on submit buttons are formaction, formenctype, formmethod, formnovalidate, and formtarget. When omitted, they default to the values given on the corresponding attributes on the form element.


The action and formaction content attributes, if specified, must have a value that is a valid non-empty URL potentially surrounded by spaces.

The action of an element is the value of the element's formaction attribute, if the element is a submit button and has such an attribute, or the value of its form owner's action attribute, if it has one, or else the empty string.


The method and formmethod content attributes are enumerated attributes with the following keywords and states:

The missing value default for these attributes is the GET state.

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.


The enctype and formenctype content attributes are enumerated attributes with the following keywords and states:

The missing value default for these attributes is the application/x-www-form-urlencoded 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 and formtarget content attributes, if specified, must have values that are valid browsing context names or keywords.

The target of an element is the value of the element's formtarget attribute, if the element is a submit button and has such an attribute; or the value of its form owner's target attribute, if it has such an attribute; or, if the Document contains a base element with a target attribute, then the value of the target attribute of the first such base element; or, if there is no such element, the empty string.


The novalidate and formnovalidate content attributes are boolean attributes. If present, they indicate that the form is not to be validated during submission.

The no-validate state of an element is true if the element is a submit button and the element's formnovalidate attribute is present, or if the element's form owner's novalidate attribute is present, and false otherwise.

This attribute is useful to include "save" buttons on forms that have validation constraints, to allow users to save their progress even though they haven't fully entered the data in the form. The following example shows a simple form that has two required fields. There are three buttons: one to submit the form, which requires both fields to be filled in; one to save the form so that the user can come back and fill it in later; and one to cancel the form altogether.

<form action="editor.cgi" method="post">
 <p><label>Name: <input required name=fn></label></p>
 <p><label>Essay: <textarea required name=essay></textarea></label></p>
 <p><input type=submit name=submit value="Submit essay"></p>
 <p><input type=submit formnovalidate name=save value="Save essay"></p>
 <p><input type=submit formnovalidate name=cancel value="Cancel"></p>
</form>

The action IDL attribute must reflect the content attribute of the same name, except that on getting, when the content attribute is missing or its value is the empty string, the document's address must be returned instead. The target IDL attribute must reflect the content attribute of the same name. The method and enctype IDL attributes must reflect the respective content attributes of the same name, limited to only known values. The encoding IDL attribute must reflect the enctype content attribute, limited to only known values. The noValidate IDL attribute must reflect the novalidate content attribute. The formAction IDL attribute must reflect the formaction content attribute, except that on getting, when the content attribute is missing or its value is the empty string, the document's address must be returned instead. The formEnctype IDL attribute must reflect the formenctype content attribute, limited to only known values. The formMethod IDL attribute must reflect the formmethod content attribute, limited to only known values. The formNoValidate IDL attribute must reflect the formnovalidate content attribute. The formTarget IDL attribute must reflect the formtarget content attribute.

4.10.19.7 Submitting element directionality

A form control dirname attribute on a form control element enables the submission of the directionality of the element, and gives the name of the field that contains this value during form submission. If such an attribute is specified, its value must not be the empty string.