HTML5

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

The click() method must run synthetic click activation steps on the element.

When an element is focused, key events received by the document must be targeted at that element. There may be no element focused; when no element is focused, key events received by the document must be targeted at the body element, if there is one, or else at the Document's root element, if there is one. If there is no root element, key events must not be fired.

User agents may track focus for each browsing context or Document individually, or may support only one focused element per top-level browsing context — user agents should follow platform conventions in this regard.

Which elements within a top-level browsing context currently have focus must be independent of whether or not the top-level browsing context itself has the system focus.

When a child browsing context is focused, its browsing context container must also have focus.

When an element is focused, the element matches the CSS :focus pseudo-class.

Each element can have a tabindex focus flag set, as defined below. This flag is a factor that contributes towards determining whether an element is focusable, as described in the next section.

If the attribute is specified, it must be parsed using the rules for parsing integers. The attribute's values have the following meanings:

If the attribute is omitted or parsing the value returns an error

The user agent should follow platform conventions to determine if the element's tabindex focus flag is set and, if so, whether the element can be reached using sequential focus navigation, and if so, what its relative order should be.

Modulo platform conventions, it is suggested that for the following elements, the tabindex focus flag be set:

• a elements that have an href attribute
• link elements that have an href attribute
• button elements
• input elements whose type attribute are not in the Hidden state
• select elements
• textarea elements
• Editing hosts
• Browsing context containers

One valid reason to ignore the platform conventions and always allow an element to be focused (by setting its tabindex focus flag) would be if the user's only mechanism for activating an element is through a keyboard action that triggers the focused element.

If the value is a negative integer

The user agent must set the element's tabindex focus flag, but should not allow the element to be reached using sequential focus navigation.

One valid reason to ignore the requirement that sequential focus navigation not allow the author to lead to the element would be if the user's only mechanism for moving the focus is sequential focus navigation. For instance, a keyboard-only user would be unable to click on a text field with a negative tabindex, so that user's user agent would be well justified in allowing the user to tab to the control regardless.

If the value is a zero

The user agent must set the element's tabindex focus flag, should allow the element to be reached using sequential focus navigation, and should follow platform conventions to determine the element's relative order.

If the value is greater than zero

The user agent must set the element's tabindex focus flag, should allow the element to be reached using sequential focus navigation, and should place the element in the sequential focus navigation order so that it is:

• before any focusable element whose tabindex attribute has been omitted or whose value, when parsed, returns an error,
• before any focusable element whose tabindex attribute has a value equal to or less than zero,
• after any element whose tabindex attribute has a value greater than zero but less than the value of the tabindex attribute on the element,
• after any element whose tabindex attribute has a value equal to the value of the tabindex attribute on the element but that is earlier in the document in tree order than the element,
• before any element whose tabindex attribute has a value equal to the value of the tabindex attribute on the element but that is later in the document in tree order than the element, and
• before any element whose tabindex attribute has a value greater than the value of the tabindex attribute on the element.

An element that has its tabindex focus flag set but does not otherwise have an activation behavior defined has an activation behavior that does nothing.

This means that an element that is only focusable because of its tabindex attribute will fire a click event in response to a non-mouse activation (e.g. hitting the "enter" key while the element is focused).

The tabIndex IDL attribute must reflect the value of the tabindex content attribute. Its default value is 0 for elements that are focusable and −1 for elements that are not focusable.

7.4.2 Focus management

An element is focusable if all of the following conditions are met:

• The element's tabindex focus flag is set.
• The element is either being rendered or is a descendant of a canvas element that represents embedded content.
• The element is not inert.
• The element is not disabled.

In addition, each shape that is generated for an area element, any user-agent-provided interface components of media elements (e.g. a play button), and distinct user interface components of form controls (e.g. "up" and "down" buttons on an <input type=number> spin control), should be focusable, unless platform conventions dictate otherwise or unless their corresponding element is disabled. (A single area element can correspond to multiple shapes, since image maps can be reused with multiple images on a page.)

Notwithstanding the above, user agents may make any element or part of an element focusable, especially to aid with accessibility or to better match platform conventions.

The focusing steps for an element are as follows:

1. If the element is not in a Document, or if the element's Document has no browsing context, or if the element's Document's browsing context has no top-level browsing context, or if the element is not focusable, or if the element is already focused, then abort these steps.

2. If focusing the element will remove the focus from another element, then run the unfocusing steps for that element.

3. Make the element the currently focused element in its top-level browsing context.

   Some elements, most notably area, can correspond to more than one distinct focusable area. If a particular area was indicated when the element was focused, then that is the area that must get focus; otherwise, e.g. when using the focus() method, the first such region in tree order is the one that must be focused.

4. The user agent may apply relevant platform-specific conventions for focusing widgets.

   For example, some platforms select the contents of a text field when that field is focused.

5. Fire a simple event named focus at the element.

User agents must synchronously run the focusing steps for an element whenever the user moves the focus to a focusable element.

The unfocusing steps for an element are as follows:

1. If the element is an input element, and the change event applies to the element, and the element does not have a defined activation behavior, and the user has changed the element's value or its list of selected files while the control was focused without committing that change, then fire a simple event that bubbles named change at the element.

2. Unfocus the element.

3. Fire a simple event named blur at the element.

When an element that is focused stops being a focusable element, or stops being focused without another element being explicitly focused in its stead, the user agent should synchronously run the unfocusing steps for the affected element only.

For example, this might happen because the element is removed from its Document, or has a hidden attribute added. It would also happen to an input element when the element gets disabled.

The activeElement attribute on Document objects must return the element in the document that is focused. If no element in the Document is focused, this must return the body element.

When a child browsing context is focused, its browsing context container is also focused, by definition. For example, if the user moves the focus to a text field in an iframe, the iframe is the element with focus in the parent browsing context.

The hasFocus() method on Document objects must return true if the Document's browsing context is focused, and all its ancestor browsing contexts are also focused, and the top-level browsing context has the system focus. If the Document has no browsing context or if its browsing context has no top-level browsing context, then the method will always return false.

The focus() method on the Window object, when invoked, provides a hint to the user agent that the script believes the user might be interested in the contents of the browsing context of the Window object on which the method was invoked.

User agents are encouraged to have this focus() method trigger some kind of notification.

The blur() method on the Window object, when invoked, provides a hint to the user agent that the script believes the user probably is not currently interested in the contents of the browsing context of the Window object on which the method was invoked, but that the contents might become interesting again in the future.

User agents are encouraged to ignore calls to this blur() method entirely.

Historically the focus() and blur() methods actually affected the system focus, but hostile sites widely abuse this behavior to the user's detriment.

The focus() method, when invoked, must run the following algorithm:

1. If the element is marked as locked for focus, then abort these steps.

2. Mark the element as locked for focus.

3. Run the focusing steps for the element.

4. Unmark the element as locked for focus.

The blur() method, when invoked, should run the unfocusing steps for the element on which the method was called instead. User agents may selectively or uniformly ignore calls to this method for usability reasons.

For example, if the blur() method is unwisely being used to remove the focus ring for aesthetics reasons, the page would become unusable by keyboard users. Ignoring calls to this method would thus allow keyboard users to interact with the page.

7.5.3 Processing model

An element's assigned access key is a key combination derived from the element's accesskey content attribute. Initially, an element must not have an assigned access key.

Whenever an element's accesskey attribute is set, changed, or removed, the user agent must update the element's assigned access key by running the following steps:

1. If the element has no accesskey attribute, then skip to the fallback step below.

2. Otherwise, split the attribute's value on spaces, and let keys be the resulting tokens.

3. For each value in keys in turn, in the order the tokens appeared in the attribute's value, run the following substeps:

   1. If the value is not a string exactly one Unicode code point in length, then skip the remainder of these steps for this value.

   2. If the value does not correspond to a key on the system's keyboard, then skip the remainder of these steps for this value.

   3. If the user agent can find a mix of zero or more modifier keys that, combined with the key that corresponds to the value given in the attribute, can be used as the access key, then the user agent may assign that combination of keys as the element's assigned access key and abort these steps.

4. Fallback: Optionally, the user agent may assign a key combination of its choosing as the element's assigned access key and then abort these steps.

5. If this step is reached, the element has no assigned access key.

Once a user agent has selected and assigned an access key for an element, the user agent should not change the element's assigned access key unless the accesskey content attribute is changed or the element is moved to another Document.

User agents might expose elements that have an accesskey attribute in other ways as well, e.g. in a menu displayed in response to a specific key combination.

The accessKey IDL attribute must reflect the accesskey content attribute.

The accessKeyLabel IDL attribute must return a string that represents the element's assigned access key, if any. If the element does not have one, then the IDL attribute must return the empty string.

The contentEditable IDL attribute, on getting, must return the string "true" if the content attribute is set to the true state, "false" if the content attribute is set to the false state, and "inherit" otherwise. On setting, if the new value is an ASCII case-insensitive match for the string "inherit" then the content attribute must be removed, if the new value is an ASCII case-insensitive match for the string "true" then the content attribute must be set to the string "true", if the new value is an ASCII case-insensitive match for the string "false" then the content attribute must be set to the string "false", and otherwise the attribute setter must throw a SyntaxError exception.

The isContentEditable IDL attribute, on getting, must return true if the element is either an editing host or editable, and false otherwise.

Documents have a designMode, which can be either enabled or disabled.

The designMode IDL attribute on the Document object takes two values, "on" and "off". On setting, the new value must be compared in an ASCII case-insensitive manner to these two values; if it matches the "on" value, then designMode must be enabled, and if it matches the "off" value, then designMode must be disabled. Other values must be ignored.

On getting, if designMode is enabled, the IDL attribute must return the value "on"; otherwise it is disabled, and the attribute must return the value "off".

The last state set must persist until the document is destroyed or the state is changed. Initially, documents must have their designMode disabled.

When the designMode changes from being disabled to being enabled, the user agent must synchronously reset the document's active range's start and end boundary points to be at the start of the Document and then run the focusing steps for the root element of the Document, if any.

User agents can support the checking of spelling and grammar of editable text, either in form controls (such as the value of textarea elements), or in elements in an editing host (e.g. using contenteditable).

For each element, user agents must establish a default behavior, either through defaults or through preferences expressed by the user. There are three possible default behaviors for each element:

true-by-default

The element will be checked for spelling and grammar if its contents are editable.

false-by-default

The element will never be checked for spelling and grammar.

inherit-by-default

The element's default behavior is the same as its parent element's. Elements that have no parent element cannot have this as their default behavior.

The spellcheck IDL attribute, on getting, must return true if the element's spellcheck content attribute is in the true state, or if the element's spellcheck content attribute is in the default state and the element's default behavior is true-by-default, or if the element's spellcheck content attribute is in the default state and the element's default behavior is inherit-by-default and the element's parent element's spellcheck IDL attribute would return true; otherwise, if none of those conditions applies, then the attribute must instead return false.

The spellcheck IDL attribute is not affected by user preferences that override the spellcheck content attribute, and therefore might not reflect the actual spellchecking state.

On setting, if the new value is true, then the element's spellcheck content attribute must be set to the literal string "true", otherwise it must be set to the literal string "false".

User agents must only consider the following pieces of text as checkable for the purposes of this feature:

• The value of input elements whose type attributes are in the Text, Search, URL, or E-mail states and that are mutable (i.e. that do not have the readonly attribute specified and that are not disabled).
• The value of textarea elements that do not have a readonly attribute and that are not disabled.
• Text in Text nodes that are children of editing hosts or editable elements.
• Text in attributes of editable elements.

For text that is part of a Text node, the element with which the text is associated is the element that is the immediate parent of the first character of the word, sentence, or other piece of text. For text in attributes, it is the attribute's element. For the values of input and textarea elements, it is the element itself.

To determine if a word, sentence, or other piece of text in an applicable element (as defined above) is to have spelling- and grammar-checking enabled, the UA must use the following algorithm:

1. If the user has disabled the checking for this text, then the checking is disabled.
2. Otherwise, if the user has forced the checking for this text to always be enabled, then the checking is enabled.
3. Otherwise, if the element with which the text is associated has a spellcheck content attribute, then: if that attribute is in the true state, then checking is enabled; otherwise, if that attribute is in the false state, then checking is disabled.
4. Otherwise, if there is an ancestor element with a spellcheck content attribute that is not in the default state, then: if the nearest such ancestor's spellcheck content attribute is in the true state, then checking is enabled; otherwise, checking is disabled.
5. Otherwise, if the element's default behavior is true-by-default, then checking is enabled.
6. Otherwise, if the element's default behavior is false-by-default, then checking is disabled.
7. Otherwise, if the element's parent element has its checking enabled, then checking is enabled.
8. Otherwise, checking is disabled.

If the checking is enabled for a word/sentence/text, the user agent should indicate spelling and grammar errors in that text. User agents should take into account the other semantics given in the document when suggesting spelling and grammar corrections. User agents may use the language of the element to determine what spelling and grammar rules to use, or may use the user's preferred language settings. UAs should use input element attributes such as pattern to ensure that the resulting value is valid, where possible.

If checking is disabled, the user agent should not indicate spelling or grammar errors for that text.

Even when checking is enabled, user agents may opt to not report spelling or grammar errors in text that the user agent deems the user has no interest in having checked (e.g. text that was already present when the page was loaded, or that the user did not type, or text in controls that the user has not focused, or in parts of e-mail addresses that the user agent is not confident were misspelt).

<div contenteditable="true">
 <span spellcheck="false" id="a">Hell</span><em>o!</em>
</div>

<p spellcheck="true">
 <label>Name: <input spellcheck=" false" id="b"></label>
</p>