HTML

Living Standard — Last Updated 7 November 2017

1. 6 User interaction
   1. 6.1 The hidden attribute
   2. 6.2 Inert subtrees
   3. 6.3 Activation
   4. 6.4 Focus
      1. 6.4.1 Introduction
      2. 6.4.2 Data model
      3. 6.4.3 The tabindex attribute
      4. 6.4.4 Processing model
      5. 6.4.5 Sequential focus navigation
      6. 6.4.6 Focus management APIs
   5. 6.5 Assigning keyboard shortcuts
      1. 6.5.1 Introduction
      2. 6.5.2 The accesskey attribute
      3. 6.5.3 Processing model
   6. 6.6 Editing
      1. 6.6.1 Making document regions editable: The contenteditable content attribute
      2. 6.6.2 Making entire documents editable: the designMode IDL attribute
      3. 6.6.3 Best practices for in-page editors
      4. 6.6.4 Editing APIs
      5. 6.6.5 Spelling and grammar checking

6 User interaction

6.1 The hidden attribute

All HTML elements may have the hidden content attribute set. The hidden attribute is a boolean attribute. When specified on an element, it indicates that the element is not yet, or is no longer, directly relevant to the page's current state, or that it is being used to declare content to be reused by other parts of the page as opposed to being directly accessed by the user. User agents should not render elements that have the hidden attribute specified. This requirement may be implemented indirectly through the style layer. For example, an HTML+CSS user agent could implement these requirements using the rules suggested in the Rendering section.

Because this attribute is typically implemented using CSS, it's also possible to override it using CSS. For instance, a rule that applies 'display: block' to all elements will cancel the effects of the hidden attribute. Authors therefore have to take care when writing their style sheets to make sure that the attribute is still styled as expected.

  <h1>The Example Game</h1>
  <section id="login">
   <h2>Login</h2>
   <form>
    ...
    <!-- calls login() once the user's credentials have been checked -->
   </form>
   <script>
    function login() {
      // switch screens
      document.getElementById('login').hidden = true;
      document.getElementById('game').hidden = false;
    }
   </script>
  </section>
  <section id="game" hidden>
   ...
  </section>

The hidden attribute must not be used to hide content that could legitimately be shown in another presentation. For example, it is incorrect to use hidden to hide panels in a tabbed dialog, because the tabbed interface is merely a kind of overflow presentation — one could equally well just show all the form controls in one big page with a scrollbar. It is similarly incorrect to use this attribute to hide content just from one presentation — if something is marked hidden, it is hidden from all presentations, including, for instance, screen readers.

Elements that are not themselves hidden must not hyperlink to elements that are hidden. The for attributes of label and output elements that are not themselves hidden must similarly not refer to elements that are hidden. In both cases, such references would cause user confusion.

Elements and scripts may, however, refer to elements that are hidden in other contexts.

Elements in a section hidden by the hidden attribute are still active, e.g. scripts and form controls in such sections still execute and submit respectively. Only their presentation to the user changes.

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

6.2 Inert subtrees

This section does not define or create any content attribute named "inert". This section merely defines an abstract concept of inertness.

A node (in particular elements and text nodes) can be marked as inert. When a node is inert, then the user agent must act as if the node was absent for the purposes of targeting user interaction events, may ignore the node for the purposes of text search user interfaces (commonly known as "find in page"), and may prevent the user from selecting text in that node. User agents should allow the user to override the restrictions on search and text selection, however.

For example, consider a page that consists of just a single inert paragraph positioned in the middle of a body. If a user moves their pointing device from the body over to the inert paragraph and clicks on the paragraph, no mouseover event would be fired, and the mousemove and click events would be fired on the body element rather than the paragraph.

When a node is inert, it generally cannot be focused. Inert nodes that are commands will also get disabled.

While a browsing context container is marked as inert, its nested browsing context's active document, and all nodes in that Document, must be marked as inert.

A Document document is blocked by a modal dialog subject if subject is the topmost dialog element in document's top layer. While document is so blocked, every node that is connected to document, with the exception of the subject element and its shadow-including descendants, must be marked inert. (The elements excepted by this paragraph can additionally be marked inert through other means; being part of a modal dialog does not "protect" a node from being marked inert.)

The dialog element's showModal() method causes this mechanism to trigger, by adding the dialog element to its node document's top layer.

6.3 Activation

Certain elements in HTML have an activation behavior, which means that the user can activate them. This is always caused by a click event.

The user agent should allow the user to manually trigger elements that have an activation behavior, for instance using keyboard or voice input, or through mouse clicks. When the user triggers an element with a defined activation behavior in a manner other than clicking it, the default action of the interaction event must be to fire a click event at the element.

An algorithm is triggered by user activation if any of the following conditions is true:

• The task in which the algorithm is running is currently processing an activation behavior whose click event's isTrusted attribute is true.

• The task in which the algorithm is running is currently running the event listener for an event whose isTrusted attribute is true and whose type is one of:

  • change
  • click
  • dblclick
  • mouseup
  • pointerup
  • reset
  • submit
  • touchend

• The task in which the algorithm is running was queued by an algorithm that was triggered by user activation, and the chain of such algorithms started within a user-agent defined timeframe.

  For example, if a user clicked a button, it might be acceptable for a popup to result from that after 4 seconds, but it would likely not be acceptable for a popup to result from that after 4 hours.

element . click()

Acts as if the element was clicked.

Each element has an associated click in progress flag, which is initially unset.

The click() method must run the following steps:

1. If this element is a form control that is disabled, then abort these steps.

2. If this element's click in progress flag is set, then abort these steps.

3. Set this element's click in progress flag.

4. Fire a synthetic mouse event at this element, with the not trusted flag set.

5. Unset this element's click in progress flag.

6.4 Focus

6.4.1 Introduction

This section is non-normative.

An HTML user interface typically consists of multiple interactive widgets, such as form controls, scrollable regions, links, dialog boxes, browser tabs, and so forth. These widgets form a hierarchy, with some (e.g. browser tabs, dialog boxes) containing others (e.g. links, form controls).

When interacting with an interface using a keyboard, key input is channeled from the system, through the hierarchy of interactive widgets, to an active widget, which is said to be focused.

Keyboard events are always targeted at this focused element.

6.4.2 Data model

The term focusable area is used to refer to regions of the interface that can become the target of keyboard input. Focusable areas can be elements, parts of elements, or other regions managed by the user agent.

Each focusable area has a DOM anchor, which is a Node object that represents the position of the focusable area in the DOM. (When the focusable area is itself a Node, it is its own DOM anchor.) The DOM anchor is used in some APIs as a substitute for the focusable area when there is no other DOM object to represent the focusable area.

The following table describes what objects can be focusable areas. The cells in the left column describe objects that can be focusable areas; the cells in the right column describe the DOM anchors for those elements. (The cells that span both columns are non-normative examples.)

<map id=wallmap><area alt="Enter Door" coords="10,10,100,200" href="door.html"></map>
...
<img src="images/innerwall.jpeg" alt="There is a white wall here, with a door." usemap="#wallmap">
...
<img src="images/outerwall.jpeg" alt="There is a red wall here, with a door." usemap="#wallmap">

A browsing context container (e.g. an iframe) is a focusable area, but key events routed to a browsing context container get immediately routed to the nested browsing context's active document. Similarly, in sequential focus navigation a browsing context container essentially acts merely as a placeholder for its nested browsing context's active document.

The following create control groups:

• Document object that have browsing contexts.
• dialog elements that have an open attribute specified and that are being rendered.

The corresponding Document object or dialog element is the created control group's owner object. (There is always a 1-to-1 mapping of control groups to control group owner objects.)

Each focusable area belongs to a single control group as follows. If the DOM anchor of a focusable area is a control group owner object, then that focusable area belongs to that control group owner object's control group. Otherwise, the focusable area belongs to its DOM anchor's nearest ancestor control group owner object's control group.

It is possible for a control group to be empty, i.e. for it to have no focusable areas.

An element is expressly inert if it is inert and its nearest ancestor control group owner object is not inert.

Each control group owner object can also act as the manager of a dialog group.

Each dialog element that has an open attribute specified and that is being rendered (i.e. that is a control group owner object) and is not expressly inert belongs to the dialog group whose manager is the dialog element's nearest ancestor control group owner object.

If no dialog element has a particular control group owner object as its nearest ancestor control group owner object, then that control group owner object has no dialog group.

Each dialog group can have a dialog designated as the focused dialog of the dialog group. Which dialog is so designated changes over time, based on algorithms in this specification.

Elements in dialog groups are ordered in tree order.

One focusable area in each non-empty control group is designated the focused area of the control group. Which control is so designated changes over time, based on algorithms in this specification. If a control group is empty, it has no focused area.

Focusable areas in control groups are ordered relative to the tree order of their DOM anchors. Focusable areas with the same DOM anchor in a control group are ordered relative to their CSS box's relative positions in a pre-order, depth-first traversal of the box tree. [CSS]

The currently focused area of a top-level browsing context at any particular time is the focusable area or dialog returned by this algorithm:

1. Let candidate be the Document of the top-level browsing context.

2. If candidate has a dialog group with a designated focused dialog of the dialog group, then let candidate be the designated focused dialog of the dialog group, and redo this step.

   Otherwise, if candidate has a non-empty control group, and the designated focused area of the control group is a browsing context container with a non-null nested browsing context, then let candidate be the active document of that browsing context container's nested browsing context, and redo this step.

   Otherwise, if candidate has a non-empty control group, let candidate be the designated focused area of the control group.

3. Return candidate.

An element that is the DOM anchor of a focusable area is said to gain focus when that focusable area becomes the currently focused area of a top-level browsing context. When an element is the DOM anchor of a focusable area of the currently focused area of a top-level browsing context, it is focused.

The focus chain of a focusable area or control group owner object subject is the ordered list constructed as follows:

1. Let current object be subject.

2. Let output be an empty list.

3. Loop: Append current object to output.

4. If current object is an area element's shape, append that area element to output.

   Otherwise, if current object is a focusable area whose DOM anchor is an element that is not current object itself, append that DOM anchor element to output.

5. If current object is a dialog object in a dialog group, let current object be that dialog group's manager, and return to the step labeled loop.

   Otherwise, if current object is a focusable area, let current object be that focusable area's control group's owner object, and return to the step labeled loop.

   Otherwise, if current object is a Document in a nested browsing context, let current object be its browsing context container, and return to the step labeled loop.

6. Return output.

   The chain starts with subject and (if subject is or can be the currently focused area of a top-level browsing context) continues up the focus hierarchy up to the Document of the top-level browsing context.

6.4.3 The tabindex attribute

The tabindex content attribute allows authors to indicate that an element is supposed to be focusable, and whether it is supposed to be reachable using sequential focus navigation and, if so, what is to be the relative order of the element for the purposes of sequential focus navigation. The name "tab index" comes from the common use of the "tab" key to navigate through the focusable elements. The term "tabbing" refers to moving forward through the focusable elements that can be reached using sequential focus navigation.

When the attribute is omitted, the user agent applies defaults. (There is no way to make an element that is being rendered be not focusable at all without disabling it or making it inert.)

The tabindex attribute, if specified, must have a value that is a valid integer. Positive numbers specify the relative position of the element's focusable areas in the sequential focus navigation order, and negative numbers indicate that the control is to be unreachable by sequential focus navigation.

Developers should use caution when using values other than 0 or −1 for their tabindex attributes as this is complicated to do correctly.

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 a focusable area, as described in the previous section.

If the tabindex attribute is specified on an element, it must be parsed using the rules for parsing integers. The attribute's values, or lack thereof, must be interpreted as follows:

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 and any focusable areas that have the element as their DOM anchor can be reached using sequential focus navigation, and if so, what their relative position in the sequential focus navigation order is to 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
• summary elements that are the first summary element child of a details element
• 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
• Browsing context containers

If the value is a negative integer

The user agent must set the element's tabindex focus flag, but should omit the element from the sequential focus navigation order.

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 control 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 and any focusable areas that have the element as their DOM anchor to be reached using sequential focus navigation, following platform conventions to determine the element's relative position in the sequential focus navigation order.

If the value is greater than zero

The user agent must set the element's tabindex focus flag, should allow the element and any focusable areas that have the element as their DOM anchor to be reached using sequential focus navigation, and should place the element — referenced as candidate below — and the aforementioned focusable areas in the sequential focus navigation order so that, relative to other focusable areas in the sequential focus navigation order, they are:

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

An element with the tabindex attribute specified is interactive content.

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.

6.4.4 Processing model

The focusing steps for an object new focus target that is either a focusable area, or an element that is not a focusable area, or a browsing context, are as follows. They can optionally be run with a fallback target.

1. If new focus target is neither a dialog element that has an open attribute specified and that is being rendered (i.e. that is a control group owner object), nor a focusable area, then run the first matching set of steps from the following list:

   If new focus target is an area element with one or more shapes that are focusable areas

   Let new focus target be the shape corresponding to the first img element in tree order that uses the image map to which the area element belongs.

   If new focus target is an element with one or more scrollable regions that are focusable areas

   Let new focus target be the element's first scrollable region, according to a pre-order, depth-first traversal of the box tree. [CSS]

   If new focus target is the document element of its Document

   Let new focus target be the Document's viewport.

   If new focus target is a browsing context

   Let new focus target be the browsing context's active document.

   If new focus target is a browsing context container with a non-null nested browsing context

   Let new focus target be the browsing context container's nested browsing context's active document.

   Otherwise

   If no fallback target was specified, abort the focusing steps.

   Otherwise, let new focus target be the fallback target.

2. If new focus target is a control group owner object that is not a focusable area, but does have a dialog group, and that dialog group has a designated focused dialog, then let new focus target be the focused dialog of the dialog group, and redo this step.

   Otherwise, if new focus target is a control group owner object that is not a focusable area, and its control group is not empty, then designate new focus target as the focused area of the control group, and redo this step.

   Otherwise, if new focus target is a browsing context container with non-null nested browsing context, then let new focus target be the nested browsing context's active document, and redo this step.

   A dialog element can be both a control group owner object and a focusable area, if it has both an open attribute specified and a tabindex attribute specified and is being rendered.

3. If new focus target is a focusable area and its DOM anchor is inert, then abort these steps.

4. If new focus target is the currently focused area of a top-level browsing context, then abort these steps.

5. Let old chain be the focus chain of the currently focused area of the top-level browsing context in which new focus target finds itself.

6. Let new chain be the focus chain of new focus target.

7. Run the focus update steps with old chain, new chain, and new focus target respectively.

User agents must immediately run the focusing steps for a focusable area, dialog, or browsing context candidate whenever the user attempts to move the focus to candidate.

The unfocusing steps for an object old focus target that is either a focusable area or an element that is not a focusable area are as follows:

1. If old focus target is inert, then abort these steps.

2. If old focus target is an area element and one of its shapes is the currently focused area of a top-level browsing context, or, if old focus target is an element with one or more scrollable regions, and one of them is the currently focused area of a top-level browsing context, then let old focus target be that currently focused area of a top-level browsing context.

3. Let old chain be the focus chain of the currently focused area of a top-level browsing context.

4. If old focus target is not one of the entries in old chain, then abort these steps.

5. If old focus target is a dialog in a dialog group, and the dialog group manager has a non-empty control group, then let new focus target be the designated focused area of that focus group.

   Otherwise, if old focus target is a focusable area, then let new focus target be the first focusable area of its control group (if the control group owner object is a Document, this will always be a viewport).

   Otherwise, let new focus target be null.

6. If new focus target is not null, then run the focusing steps for new focus target.

When the currently focused area of a top-level browsing context is somehow unfocused without another element being explicitly focused in its stead, the user agent must immediately run the unfocusing steps for that object.

The unfocusing steps do not always result in the focus changing, even when applied to the currently focused area of a top-level browsing context. For example, if the currently focused area of a top-level browsing context is a viewport, then it will usually keep its focus regardless until another focusable area is explicitly focused with the focusing steps.

When a focusable area is added to an empty control group, it must be designated the focused area of the control group.

When a dialog group is formed, if the dialog group manager has an empty control group, the first non-inert dialog in the dialog group, if any, or else the first dialog in the dialog group regardless of inertness, must be designated the focused dialog of the dialog group.

Focus fixup rule one: When the designated focused area of a control group is removed from that control group in some way (e.g. it stops being a focusable area, it is removed from the DOM, it becomes expressly inert, etc), and the control group is still not empty: designate the first non-inert focusable area in that control group to be the new focused area of the control group, if any; if they are all inert, then designate the first focusable area in that control group to be the new focused area of the control group regardless of inertness. If such a removal instead results in the control group being empty, then there is simply no longer a focused area of the control group.

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

In a Document without dialog elements, whose focused area is a button element, removing, disabling, or hiding that button would cause the page's new focused area to be the viewport of the Document. This would, in turn, be reflected through the activeElement API as the body element.

Focus fixup rule two: When a dialog group has no designated focused dialog of the dialog group, and its dialog group manager's control group changes from being non-empty to being empty, the first non-inert dialog in the dialog group, if any, or else the first dialog in the dialog group regardless of inertness, must be designated the focused dialog of the dialog group.

Focus fixup rule three: When the designated focused dialog of a dialog group is removed from that dialog group in some way (e.g. it stops being rendered, it loses its open attribute, it becomes expressly inert, etc), and there is still a dialog group (because the dialog in question was not the last dialog in that dialog group): if the dialog group's manager's control group is non-empty, let there be no designated focused dialog of the dialog group any more; otherwise (in the case that the control group is empty), designate the first non-inert dialog in the dialog group to be the focused dialog of the dialog group, or, if they are all inert, designate the first dialog in the dialog group to be the focused dialog of the dialog group regardless of inertness.

When the currently focused area of a top-level browsing context was a focusable area but stops being a focusable area, or when it was a dialog in a dialog group and stops being part of that dialog group, or when it starts being inert, the user agent must run the following steps:

1. Let old focus target be whatever the currently focused area of the top-level browsing context was immediately before this algorithm became applicable (e.g. before the element was disabled, or the dialog was closed, or whatever caused this algorithm to run).

2. Let old chain be the focus chain of the currently focused area of the top-level browsing context at the same time.

3. Make sure that the changes implied by the focus fixup rules one, two, and three above are applied.

4. Let new focus target be the currently focused area of a top-level browsing context.

5. If old focus target and new focus target are the same, abort these steps.

6. Let new chain be the focus chain of new focus target.

7. Run the focus update steps with old chain, new chain, and new focus target respectively.

The focus update steps, given an old chain, a new chain, and a new focus target respectively, are as follows:

1. If the last entry in old chain and the last entry in new chain are the same, pop the last entry from old chain and the last entry from new chain and redo this step.

2. For each entry entry in old chain, in order, run these substeps:

   1. If entry 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 (such that it is different to what it was when the control was first focused), then fire an event named change at the element, with the bubbles attribute initialized to true.

   2. If entry is an element, let blur event target be entry.

      If entry is a Document object, let blur event target be that Document object's Window object.

      Otherwise, let blur event target be null.

   3. If entry is the last entry in old chain, and entry is an Element, and the last entry in new chain is also an Element, then let related blur target be the last entry in new chain. Otherwise, let related blur target be null.

   4. If blur event target is not null, fire a focus event named blur at blur event target, with related blur target as the related target.

      In some cases, e.g. if entry is an area element's shape, a scrollable region, or a viewport, no event is fired.

3. Apply any relevant platform-specific conventions for focusing new focus target. (For example, some platforms select the contents of a text control when that control is focused.)

4. For each entry entry in new chain, in reverse order, run these substeps:

   1. If entry is a dialog element: let entry be the designated focused dialog of its dialog group.

   2. If entry is a focusable area: designate entry as the focused area of the control group. If its control group's owner object is also a dialog group manager, then let there be no designated focused dialog in that dialog group.

      It is possible for entry to be both a dialog element and a focusable area, in which case it is its own control group owner object.

   3. If entry is an element, let focus event target be entry.

      If entry is a Document object, let focus event target be that Document object's Window object.

      Otherwise, let focus event target be null.

   4. If entry is the last entry in new chain, and entry is an Element, and the last entry in old chain is also an Element, then let related focus target be the last entry in old chain. Otherwise, let related focus target be null.

   5. If focus event target is not null, fire a focus event named focus at focus event target, with related focus target as the related target.

      In some cases, e.g. if entry is an area element's shape, a scrollable region, or a viewport, no event is fired.

To fire a focus event named e at an element t and with a given related target r, fire an event named e at t, using FocusEvent, with the relatedTarget attribute initialized to r and the view attribute initialized to t's node document's Window object.

When a key event is to be routed in a top-level browsing context, the user agent must run the following steps:

1. Let target area be the currently focused area of the top-level browsing context.

2. If target area is a focusable area, let target node be target area's DOM anchor. Otherwise, target area is a dialog; let target node be target area.

3. If target node is a Document that has a body element, then let target node be the body element of that Document.

   Otherwise, if target node is a Document object that has a non-null document element, then let target node be that document element.

4. If target node is not inert, then:

   It is possible for the currently focused area of a top-level browsing context to be inert, for example if a modal dialog is shown, and then that dialog element is made inert. It is likely to be the result of a logic error in the application, though.

   1. Let canHandle be the result of dispatching the key event at target node.

   2. If canHandle is true, then let target area handle the key event. This might include firing a click event at target node.

The has focus steps, given a Document object target, are as follows:

1. Let candidate be the Document of the top-level browsing context.

2. If candidate is target, return true and abort these steps.

3. If candidate has a dialog group with a designated focused dialog of the dialog group, then let candidate be the designated focused dialog of the dialog group, and redo this step.

   Otherwise, if candidate has a non-empty control group, and the designated focused area of the control group is a browsing context container with a non-null nested browsing context, and the active document of that browsing context container's nested browsing context is target, then return true and abort these steps.

   Otherwise, if candidate has a non-empty control group, and the designated focused area of the control group is a browsing context container with a non-null nested browsing context, then let candidate be the active document of that browsing context container's nested browsing context, and redo this step.

   Otherwise, return false and abort these steps.

6.4.5 Sequential focus navigation

Each control group has a sequential focus navigation order, which orders some or all of the focusable areas in the control group relative to each other. The order in the sequential focus navigation order does not have to be related to the order in the control group itself. If a focusable area is omitted from the sequential focus navigation order of its control group, then it is unreachable via sequential focus navigation.

There can also be a sequential focus navigation starting point. It is initially unset. The user agent may set it when the user indicates that it should be moved.

For example, the user agent could set it to the position of the user's click if the user clicks on the document contents.

When the user requests that focus move from the currently focused area of a top-level browsing context to the next or previous focusable area (e.g. as the default action of pressing the tab key), or when the user requests that focus sequentially move to a top-level browsing context in the first place (e.g. from the browser's location bar), the user agent must use the following algorithm:

1. Let starting point be the currently focused area of a top-level browsing context, if the user requested to move focus sequentially from there, or else the top-level browsing context itself, if the user instead requested to move focus from outside the top-level browsing context.

2. If there is a sequential focus navigation starting point defined and it is inside starting point, then let starting point be the sequential focus navigation starting point instead.

3. Let direction be forward if the user requested the next control, and backward if the user requested the previous control.

   Typically, pressing tab requests the next control, and pressing shift+tab requests the previous control.

4. Loop: Let selection mechanism be sequential if the starting point is a browsing context or if starting point is in its control group's sequential focus navigation order.

   Otherwise, starting point is not in its control group's sequential focus navigation order; let selection mechanism be DOM.

5. Let candidate be the result of running the sequential navigation search algorithm with starting point, direction, and selection mechanism as the arguments.

6. If candidate is not null, then run the focusing steps for candidate and abort these steps.

7. Otherwise, unset the sequential focus navigation starting point.

8. If starting point is the top-level browsing context, or a focusable area in the top-level browsing context, the user agent should transfer focus to its own controls appropriately (if any), honouring direction, and then abort these steps.

   For example, if direction is backward, then the last focusable control before the browser's rendering area would be the control to focus.

   If the user agent has no focusable controls — a kiosk-mode browser, for instance — then the user agent may instead restart these steps with the starting point being the top-level browsing context itself.

9. Otherwise, starting point is a focusable area in a nested browsing context. Let starting point be that nested browsing context's browsing context container, and return to the step labeled loop.

The sequential navigation search algorithm consists of the following steps. This algorithm takes three arguments: starting point, direction, and selection mechanism.

1. Pick the appropriate cell from the following table, and follow the instructions in that cell.

   The appropriate cell is the one that is from the column whose header describes direction and from the first row whose header describes starting point and selection mechanism.

   	direction is forward	direction is backward
   starting point is a browsing context	Let candidate be the first suitable sequentially focusable area in starting point's active document's primary control group, if any; or else null	Let candidate be the last suitable sequentially focusable area in starting point's active document's primary control group, if any; or else null
   selection mechanism is DOM	Let candidate be the first suitable sequentially focusable area in the home control group following starting point, if any; or else null	Let candidate be the last suitable sequentially focusable area in the home control group preceding starting point, if any; or else null
   selection mechanism is sequential	Let candidate be the first suitable sequentially focusable area in the home sequential focus navigation order following starting point, if any; or else null	Let candidate be the last suitable sequentially focusable area in the home sequential focus navigation order preceding starting point, if any; or else null

   A suitable sequentially focusable area is a focusable area whose DOM anchor is not inert and that is in its control group's sequential focus navigation order.

   The primary control group of a control group owner object X is the control group of X if X has no dialog group or if its dialog group has no designated focused dialog of the dialog group, otherwise, it is the primary control group of X's dialog group's designated focused dialog of the dialog group.

   The home control group is the control group to which starting point belongs.

   The home sequential focus navigation order is the sequential focus navigation order to which starting point belongs.

   The home sequential focus navigation order is the home control group's sequential focus navigation order, but is only used when the starting point is in that sequential focus navigation order (when it's not, selection mechanism will be DOM).

2. If candidate is a browsing context container with a non-null nested browsing context, then let new candidate be the result of running the sequential navigation search algorithm with candidate's nested browsing context as the first argument, direction as the second, and sequential as the third.

   If new candidate is null, then let starting point be candidate, and return to the top of this algorithm. Otherwise, let candidate be new candidate.

3. Return candidate.

6.4.6 Focus management APIs

dictionary FocusOptions {
  boolean preventScroll = false;
};

document . activeElement

Returns the deepest element in the document through which or to which key events are being routed. This is, roughly speaking, the focused element in the document.

For the purposes of this API, when a child browsing context is focused, its browsing context container is focused in the parent browsing context. For example, if the user moves the focus to a text control in an iframe, the iframe is the element returned by the activeElement API in the iframe's node document.

document . hasFocus()

Returns true if key events are being routed through or to the document; otherwise, returns false. Roughly speaking, this corresponds to the document, or a document nested inside this one, being focused.

window . focus()

Moves the focus to the window's browsing context, if any.

element . focus([ { preventScroll: true } ])

Moves the focus to the element.

If the element is a browsing context container, moves the focus to the nested browsing context instead.

By default, this method also scrolls the element into view. Providing the preventScroll option and setting it to true prevents this behavior.

element . blur()

Moves the focus to the viewport. Use of this method is discouraged; if you want to focus the viewport, call the focus() method on the Document's document element.

Do not use this method to hide the focus ring if you find the focus ring unsightly. Instead, use a CSS rule to override the 'outline' property, and provide a different way to show what element is focused. Be aware that if an alternative focusing style isn't made available, the page will be significantly less usable for people who primarily navigate pages using a keyboard, or those with reduced vision who use focus outlines to help them navigate the page.

For example, to hide the outline from links and instead use a yellow background to indicate focus, you could use:

:link:focus, :visited:focus { outline: none; background: yellow; color: black; }

The activeElement attribute on Document objects must return the value returned by the following steps:

1. Let candidate be the Document on which the method was invoked.

2. If candidate has a dialog group with a designated focused dialog of the dialog group, then let candidate be the designated focused dialog of the dialog group, and redo this step.

3. If candidate has a non-empty control group, let candidate be the designated focused area of the control group.

4. If candidate is a focusable area, let candidate be candidate's DOM anchor.

5. If candidate is a Document that has a body element, then let candidate be the body element of that Document.

   Otherwise, if candidate is a Document with a non-null document element, then let candidate be that document element.

   Otherwise, if candidate is a Document, then let candidate be null.

6. Return candidate.

The hasFocus() method on the Document object, when invoked, must return the result of running the has focus steps with the Document object as the argument.

The focus() method on the Window object, when invoked, must run the focusing steps with the Window object's browsing context. Additionally, if this browsing context is a top-level browsing context, user agents are encouraged to trigger some sort of notification to indicate to the user that the page is attempting to gain focus.

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-level focus of the system widget (e.g. tab or window) that contained the browsing context, but hostile sites widely abuse this behavior to the user's detriment.

The focus(options) method on elements, when invoked, must run the following steps:

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. If the value of the preventScroll dictionary member of options is false, then scroll the element into view with scroll behavior "auto", block flow direction position set to a UA-defined value, and inline base direction position set to a UA-defined value.

5. 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. 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.

6.5 Assigning keyboard shortcuts

6.5.1 Introduction

This section is non-normative.

Each element that can be activated or focused can be assigned a single key combination to activate it, using the accesskey attribute.

The exact shortcut is determined by the user agent, based on information about the user's keyboard, what keyboard shortcuts already exist on the platform, and what other shortcuts have been specified on the page, using the information provided in the accesskey attribute as a guide.

In order to ensure that a relevant keyboard shortcut is available on a wide variety of input devices, the author can provide a number of alternatives in the accesskey attribute.

Each alternative consists of a single character, such as a letter or digit.

User agents can provide users with a list of the keyboard shortcuts, but authors are encouraged to do so also. The accessKeyLabel IDL attribute returns a string representing the actual key combination assigned by the user agent.

<input type=button value=Collect onclick="collect()"
       accesskey="C 1" id=c>

function addShortcutKeyLabel(button) {
  if (button.accessKeyLabel != '')
    button.value += ' (' + button.accessKeyLabel + ')';
}
addShortcutKeyLabel(document.getElementById('c'));

6.5.2 The accesskey attribute

All HTML elements may have the accesskey content attribute set. The accesskey attribute's value is used by the user agent as a guide for creating a keyboard shortcut that activates or focuses the element.

If specified, the value must be an ordered set of unique space-separated tokens that are case-sensitive, each of which must be exactly one code point in length.

<nav>
 <p>
  <a title="Consortium Activities" accesskey="A" href="/Consortium/activities">Activities</a> |
  <a title="Technical Reports and Recommendations" accesskey="T" href="/TR/">Technical Reports</a> |
  <a title="Alphabetical Site Index" accesskey="S" href="/Consortium/siteindex">Site Index</a> |
  <a title="About This Site" accesskey="B" href="/Consortium/">About Consortium</a> |
  <a title="Contact Consortium" accesskey="C" href="/Consortium/contact">Contact</a>
 </p>
</nav>

<form action="/search">
 <label>Search: <input type="search" name="q" accesskey="s 0"></label>
 <input type="submit">
</form>

<input type=submit accesskey="N @ 1" value="Compose">
...
<script>
 function labelButton(button) {
   if (button.accessKeyLabel)
     button.value += ' (' + button.accessKeyLabel + ')';
 }
 var inputs = document.getElementsByTagName('input');
 for (var i = 0; i < inputs.length; i += 1) {
   if (inputs[i].type == "submit")
     labelButton(inputs[i]);
 }
</script>

6.5.3 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 ASCII whitespace, 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 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.

When the user presses the key combination corresponding to the assigned access key for an element, if the element defines a command, the command's Hidden State facet is false (visible), the command's Disabled State facet is also false (enabled), the element is in a document that has a browsing context, and neither the element nor any of its ancestors has a hidden attribute specified, then the user agent must trigger the Action of the command.

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.

6.6 Editing

6.6.1 Making document regions editable: The contenteditable content attribute

[Exposed=Window,
 NoInterfaceObject]
interface ElementContentEditable {
  [CEReactions] attribute DOMString contentEditable;
  readonly attribute boolean isContentEditable;
};

The contenteditable content attribute is an enumerated attribute whose keywords are the empty string, true, and false. The empty string and the true keyword map to the true state. The false keyword maps to the false state. In addition, there is a third state, the inherit state, which is the missing value default (and the invalid value default).

The true state indicates that the element is editable. The inherit state indicates that the element is editable if its parent is. The false state indicates that the element is not editable.

<form method=POST>
 <fieldset>
  <legend>New article</legend>
  <textarea name=article>&lt;p>Hello world.&lt;/p></textarea>
 </fieldset>
 <p><button>Publish</button></p>
</form>

<form method=POST>
 <fieldset>
  <legend>New article</legend>
  <textarea id=textarea name=article>&lt;p>Hello world.&lt;/p></textarea>
  <div id=div style="white-space: pre-wrap" hidden><p>Hello world.</p></div>
  <script>
   let textarea = document.getElementById("textarea");
   let div = document.getElementById("div");
   textarea.hidden = true;
   div.hidden = false;
   div.contentEditable = "true";
   div.oninput = (e) => {
     textarea.value = div.innerHTML;
   };
  </script>
 </fieldset>
 <p><button>Publish</button></p>
</form>

<!doctype html>
<html lang=en>
<title>Live CSS editing!</title>
<style style=white-space:pre contenteditable>
html { margin:.2em; font-size:2em; color:lime; background:purple }
head, title, style { display:block }
body { display:none }
</style>

element . contentEditable [ = value ]

Returns "true", "false", or "inherit", based on the state of the contenteditable attribute.

Can be set, to change that state.

Throws a "SyntaxError" DOMException if the new value isn't one of those strings.

element . isContentEditable

Returns true if the element is editable; otherwise, returns false.

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" DOMException.

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

6.6.2 Making entire documents editable: the designMode IDL attribute

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

document . designMode [ = value ]

Returns "on" if the document is editable, and "off" if it isn't.

Can be set, to change the document's current state. This focuses the document and resets the selection in that document.

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 immediately 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 document element of the Document, if non-null.

6.6.3 Best practices for in-page editors

Authors are encouraged to set the 'white-space' property on editing hosts and on markup that was originally created through these editing mechanisms to the value 'pre-wrap'. Default HTML whitespace handling is not well suited to WYSIWYG editing, and line wrapping will not work correctly in some corner cases if 'white-space' is left at its default value.

6.6.4 Editing APIs

The definition of the terms active range, editing host, and editable, the user interface requirements of elements that are editing hosts or editable, the execCommand(), queryCommandEnabled(), queryCommandIndeterm(), queryCommandState(), queryCommandSupported(), and queryCommandValue() methods, text selections, and the delete the selection algorithm are defined in execCommand. [EXECCOMMAND]

6.6.5 Spelling and grammar checking

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 and spellchecking is not explicitly disabled through the spellcheck attribute.

false-by-default

The element will never be checked for spelling and grammar unless spellchecking is explicitly enabled through the spellcheck attribute.

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 attribute is an enumerated attribute whose keywords are the empty string, true and false. The empty string and the true keyword map to the true state. The false keyword maps to the false state. In addition, there is a third state, the default state, which is the missing value default (and the invalid value default).

The true state indicates that the element is to have its spelling and grammar checked. The default state indicates that the element is to act according to a default behavior, possibly based on the parent element's own spellcheck state, as defined below. The false state indicates that the element is not to be checked.

element . spellcheck [ = value ]

Returns true if the element is to have its spelling and grammar checked; otherwise, returns false.

Can be set, to override the default and set the spellcheck content attribute.

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.

<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>

This specification does not define the user interface for spelling and grammar checkers. A user agent could offer on-demand checking, could perform continuous checking while the checking is enabled, or could use other interfaces.