HTML5

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

Each element has a click in progress flag, initially set to false.

The click() method must run these steps:

1. If the element's click in progress flag is set to true, then abort these steps.

2. Set the click in progress flag on the element to true.

3. If the element has a defined activation behavior, run synthetic click activation steps on the element. Otherwise, fire a click event at the element.

4. Set the click in progress flag on the element to false.

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.

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

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 is to be focusable and, if so, whether the element can be reached using sequential focus navigation, and if so, what its relative order should be.

If the value is a negative integer

The user agent must allow the element to be focused, but should not allow the element to be reached using sequential focus navigation.

If the value is a zero

The user agent must allow the element to be focused, 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 allow the element to be focused, 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 is specially focusable if the tabindex attribute's definition above defines the element to be focusable.

An element that is specially focusable 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.

7.3.2 Focus management

An element is focusable if the user agent's default behavior allows it to be focusable or if the element is specially focusable, but only if the element is either being rendered or is a descendant of a canvas element that represents embedded content.

User agents should make the following elements focusable, unless platform conventions dictate otherwise:

• a elements that have an href attribute
• link elements that have an href attribute
• button elements that are not disabled
• input elements whose type attribute are not in the Hidden state and that are not disabled
• select elements that are not disabled
• textarea elements that are not disabled
• command elements that do not have a disabled attribute
• Elements with a draggable attribute set, if that would enable the user agent to allow the user to begin a drag operations for those elements without the use of a pointing device
• Editing hosts

In addition, each shape that is generated for an area element should be focusable, unless platform conventions dictate otherwise. (A single area element can correspond to multiple shapes, since image maps can be reused with multiple images on a page.)

The user agent may also make part of a details element's rendering focusable, to enable the element to be opened or closed using keyboard input. However, this is distinct from the details or summary element being focusable.

The focusing steps 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, 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 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 focusing steps for the body element, if there is one; if there is not, then 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 HTMLDocument 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.

The hasFocus() method on HTMLDocument 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. If the element is not focusable, then abort these steps.

3. Mark the element as locked for focus.

4. If the element is not already focused, run the focusing steps for the element.

5. Unmark the element as locked for focus.

The blur() method, when invoked, should run the focusing steps for the body element, if there is one; if there is not, then it 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.

7.4.3 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 combination of modifier keys that, with the key that corresponds to the value given in the attribute, can be used as a shortcut 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.

When the user presses the key combination corresponding to the assigned access key for an element, if the element defines a command, and the command's Hidden State facet is false (visible), and the command's Disabled State facet is also false (enabled), then the user agent must trigger the Action of the command.

User agents may 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.

Specifically, if an HTML element has a contenteditable attribute set to the true state, or it has its contenteditable attribute set to the inherit state and if its nearest ancestor HTML element with the contenteditable attribute set to a state other than the inherit state has its attribute set to the true state, or if it and its ancestors all have their contenteditable attribute set to the inherit state but the Document has designMode enabled, then the UA must treat the element as editable (as described below).

Otherwise, either the HTML element has a contenteditable attribute set to the false state, or its contenteditable attribute is set to the inherit state and its nearest ancestor HTML element with the contenteditable attribute set to a state other than the inherit state has its attribute set to the false state, or all its ancestors have their contenteditable attribute set to the inherit state and the Document itself has designMode disabled; either way, the element is not editable.

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 raise a SYNTAX_ERR exception.

The isContentEditable IDL attribute, on getting, must return true if the element is editable, and false otherwise.

If an element is editable and its parent element is not, or if an element is editable and it has no parent element, then the element is an editing host. Editable elements can be nested. Editing hosts are typically focusable and typically form part of the tab order. An editing host can contain non-editable sections, these are handled as described below. An editing host can contain non-editable sections that contain further editing hosts.

When an editing host has focus, it must have a caret position that specifies where the current editing position is. It may also have a selection.

How the caret and selection are represented depends entirely on the UA.

7.5.1 User editing actions

There are several actions that the user agent should allow the user to perform while the user is interacting with an editing host. How exactly each action is triggered is not defined for every action, but when it is not defined, suggested key bindings are provided to guide implementors.

Move the caret

User agents must allow users to move the caret to any position within an editing host, even into nested editable elements. This could be triggered as the default action of keydown events with various key identifiers and as the default action of mousedown events.

Change the selection

User agents must allow users to change the selection within an editing host, even into nested editable elements. User agents may prevent selections from being made in ways that cross from editable elements into non-editable elements (e.g. by making each non-editable descendant atomically selectable, but not allowing text selection within them). This could be triggered as the default action of keydown events with various key identifiers and as the default action of mousedown events.

Insert text

This action must be triggered as the default action of a textInput event, and may be triggered by other commands as well. It must cause the user agent to insert the specified text (given by the event object's data attribute in the case of the textInput event) at the caret.

If the caret is positioned somewhere where phrasing content is not allowed (e.g. inside an empty ol element), then the user agent must not insert the text directly at the caret position. In such cases the behavior is UA-dependent, but user agents must not, in response to a request to insert text, generate a DOM that is less conformant than the DOM prior to the request.

User agents should allow users to insert new paragraphs into elements that contains only content other than paragraphs.

For example, given the markup:

<section>
 <dl>
  <dt> Ben </dt>
  <dd> Goat </dd>
 </dl>
</section>

...the user agent should allow the user to insert p elements before and after the dl element, as children of the section element.

Break block

UAs should offer a way for the user to request that the current paragraph be broken at the caret, e.g. as the default action of a keydown event whose identifier is the "Enter" key and that has no modifiers set.

The exact behavior is UA-dependent, but user agents must not, in response to a request to break a paragraph, generate a DOM that is less conformant than the DOM prior to the request.

Insert a line separator

UAs should offer a way for the user to request an explicit line break at the caret position without breaking the paragraph, e.g. as the default action of a keydown event whose identifier is the "Enter" key and that has a shift modifier set. Line separators are typically found within a poem verse or an address. To insert a line break, the user agent must insert a br element.

If the caret is positioned somewhere where phrasing content is not allowed (e.g. in an empty ol element), then the user agent must not insert the br element directly at the caret position. In such cases the behavior is UA-dependent, but user agents must not, in response to a request to insert a line separator, generate a DOM that is less conformant than the DOM prior to the request.

Delete

UAs should offer a way for the user to delete text and elements, including non-editable descendants, e.g. as the default action of keydown events whose identifiers are "U+0008" or "U+007F".

Five edge cases in particular need to be considered carefully when implementing this feature: backspacing at the start of an element, backspacing when the caret is immediately after an element, forward-deleting at the end of an element, forward-deleting when the caret is immediately before an element, and deleting a selection whose start and end points do not share a common parent node.

In any case, the exact behavior is UA-dependent, but user agents must not, in response to a request to delete text or an element, generate a DOM that is less conformant than the DOM prior to the request.

Insert, and wrap text in, semantic elements

UAs should offer the user the ability to mark text and paragraphs with semantics that HTML can express.

UAs should similarly offer a way for the user to insert empty semantic elements to subsequently fill by entering text manually.

UAs should also offer a way to remove those semantics from marked up text, and to remove empty semantic element that have been inserted.

In response to a request from a user to mark text up in italics, user agents should use the i element to represent the semantic. The em element should be used only if the user agent is sure that the user means to indicate stress emphasis.

In response to a request from a user to mark text up in bold, user agents should use the b element to represent the semantic. The strong element should be used only if the user agent is sure that the user means to indicate importance.

The exact behavior is UA-dependent, but user agents must not, in response to a request to wrap semantics around some text or to insert or remove a semantic element, generate a DOM that is less conformant than the DOM prior to the request.

Select and move non-editable elements nested inside editing hosts

UAs should offer a way for the user to move images and other non-editable parts around the content within an editing host. This may be done using the drag and drop mechanism. User agents must not, in response to a request to move non-editable elements nested inside editing hosts, generate a DOM that is less conformant than the DOM prior to the request.

Edit form controls nested inside editing hosts

When an editable form control is edited, the changes must be reflected in both its current value and its default value. For input elements this means updating the defaultValue IDL attribute as well as the value IDL attribute; for select elements it means updating the option elements' defaultSelected IDL attribute as well as the selected IDL attribute; for textarea elements this means updating the defaultValue IDL attribute as well as the value IDL attribute. (Updating the default* IDL attributes causes content attributes to be updated as well.)

User agents may perform several commands per user request; for example if the user selects a block of text and hits Enter, the UA might interpret that as a request to delete the content of the selection followed by a request to break the paragraph at that position.

User agents may add DOM changes entries to the undo transaction history of the editing host's Document object each time an action is triggered.

All of the actions defined above, whether triggered by the user or programmatically (e.g. by execCommand() commands), must fire mutation events as appropriate.

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". When it is set, 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.

When designMode is enabled, the IDL attribute must return the value "on", and when it is disabled, it 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.

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 (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 to which the readonly attribute applies, whose type attributes are not in the Password state, and that are not immutable (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 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/or 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/or 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.

<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>