← 4.10.18 Association of controls and forms – Table of contents – 4.10.19.5 Form submission →
      1. 4.10.19 Attributes common to form controls
        1. 4.10.19.1 Naming form controls
        2. 4.10.19.2 Enabling and disabling form controls
        3. 4.10.19.3 Autofocusing a form control
        4. 4.10.19.4 Limiting user input length

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.

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.

4.10.19.3 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 or as soon as the dialog within which it finds itself is shown, allowing the user to just start typing without having to manually focus the main control.

The autofocus attribute is a boolean attribute.

An element's nearest ancestor autofocus scoping root element is the element itself if the element is a dialog element, or else is the element's nearest ancestor dialog element, if any, or else is the element's root element.

There must not be two elements with the same nearest ancestor autofocus scoping root element that both have the autofocus attribute specified.

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">
4.10.19.4 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.