HTML 5.2

4.11. Interactive elements

4.11.1. The details element

Categories:

Flow content.

Sectioning root.

Interactive content.

Palpable content.

Contexts in which this element can be used:

Where flow content is expected.

Content model:

One summary element followed by flow content.

Tag omission in text/html:

Neither tag is omissible

Content attributes:

Global attributes

open - Whether the details are visible

Allowed ARIA role attribute values:

group role (default - do not set)

Allowed ARIA state and property attributes:

Global aria-* attributes

Any aria-* attributes applicable to the default role.

DOM interface:

interface HTMLDetailsElement : HTMLElement {
  attribute boolean open;
};

The details element represents a disclosure widget from which the user can obtain additional information or controls.

The details element is not appropriate for footnotes. Please see §4.13.5 Footnotes for details on how to mark up footnotes.

If the details element has a summary child element, then the first summary child element represents the summary or legend of the details element. If there is no summary child element, a user agent should provide its own legend (e.g. in English "Details" or Spanish "Detalles").

The legend text should be presented in the language determined from the computed language of the element, if available, rather than from the locale of the browser/system.

The rest of the element’s contents represents the additional information or controls.

The open content attribute is a boolean attribute. If present, it indicates that both the summary and the additional information is to be shown to the user. If the attribute is absent, only the summary is to be shown.

When the element is created, if the attribute is absent, the additional information should be hidden; if the attribute is present, that information should be shown. Subsequently, if the attribute is removed, then the information should be hidden; if the attribute is added, the information should be shown.

The user agent should allow the user to request that the additional information be shown or hidden. To honor a request for the details to be shown, the user agent must set the open attribute on the element to the empty string. To honor a request for the information to be hidden, the user agent must remove the open attribute from the element.

This ability to request that additional information be shown or hidden may simply be the activation behavior of the appropriate summary element, in the case such an element exists. However, if no such element exists, user agents can still provide this ability through some other user interface affordance.

Whenever the open attribute is added to or removed from a details element, the user agent must queue a task that runs the following steps, which are known as the details notification task steps, for this details element:

1. If another task has been queued to run the details notification task steps for this details element, then abort these steps.

   When the open attribute is toggled several times in succession, these steps essentially get coalesced so that only one event is fired.

2. Fire a simple event named toggle at the details element.

The task source for this task must be the DOM manipulation task source.

The open IDL attribute must reflect the open content attribute.

<section class="progress window">
  <h1>Copying "Really Achieving Your Childhood Dreams"</h1>
  <details>
  <summary>Copying... <progress max="375505392" value="97543282"></progress> 25%</summary>
  <dl>
    <dt>Transfer rate:</dt> <dd>452KB/s</dd>
    <dt>Local filename:</dt> <dd>/home/rpausch/raycd.m4v</dd>
    <dt>Remote filename:</dt> <dd>/var/www/lectures/raycd.m4v</dd>
    <dt>Duration:</dt> <dd>01:16:27</dd>
    <dt>Color profile:</dt> <dd>SD (6-1-6)</dd>
    <dt>Dimensions:</dt> <dd>320×240</dd>
  </dl>
  </details>
</section>

<details>
  <summary><label for=fn>Name & Extension:</label></summary>
  <p><input type=text id=fn name=fn value="Pillar Magazine.pdf">
  <p><label><input type=checkbox name=ext checked> Hide extension</label>
</details>

<style>
  details > summary { transition: color 1s; color: black; }
  details[open] > summary { color: red; }
</style>
<details>
  <summary>Automated Status: Operational</summary>
  <p>Velocity: 12m/s</p>
  <p>Direction: North</p>
</details>

4.11.2. The summary element

Categories:

None.

Contexts in which this element can be used:

As the first child of a details element.

Content model:

Either: phrasing content.

Or: one element of heading content.

Tag omission in text/html:

Neither tag is omissible

Content attributes:

Global attributes

Allowed ARIA role attribute values:

button.

Allowed ARIA state and property attributes:

Global aria-* attributes

Any aria-* attributes applicable to the allowed roles.

DOM interface:

Uses HTMLElement.

The first summary child element of a details element represents a summary, caption, or legend for the rest of the contents of the parent details element, if any.

The activation behavior of summary elements is to run the following steps:

1. If this summary element has no parent node, then abort these steps.
2. Let parent be this summary element’s parent node.
3. If parent is not a details element, then abort these steps.
4. If the open attribute is present on parent, then remove it. Otherwise, set parent’s open attribute to the empty string.

   This will then run the details notification task steps.

4.11.3. Commands

4.11.3.1. Facets

A command is the abstraction behind buttons, and links. Once a command is defined, other parts of the interface can refer to the same command, allowing many access points to a single feature to share facets such as the Disabled State.

Commands are defined to have the following facets:

Label

The name of the command as seen by the user.

Access Key

A key combination selected by the user agent that triggers the command. A command might not have an Access Key.

Hidden State

Whether the command is hidden or not.

Disabled State

Whether the command is relevant and can be triggered or not.

Action

The actual effect that triggering the command will have. This could be a scripted event handler, a URL to which to navigate, or a form submission.

User agents may expose the commands that match the following criteria:

• The Hidden State facet is false (visible)
• The element is in a Document that has an associated browsing context.
• Neither the element nor any of its ancestors has a hidden attribute specified.

User agents are encouraged to do this especially for commands that have Access Keys, as a way to advertise those keys to the user.

4.11.3.2. Using the a element to define a command

An a element with an href attribute defines a command.

The Label of the command is the string given by the element’s textContent IDL attribute.

The Access Key of the command is the element’s assigned access key, if any.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State facet of the command is true if the element or one of its ancestors is inert, and false otherwise.

The Action of the command, if the element has a defined activation behavior, is to run synthetic click activation steps on the element. Otherwise, it is just to fire a click event at the element.

4.11.3.3. Using the button element to define a command

A button element always defines a command.

The Label, Access Key, Hidden State, and Action facets of the command are determined as for a elements (see the previous section).

The Disabled State of the command is true if the element or one of its ancestors is inert, or if the element’s disabled state is set, and false otherwise.

4.11.3.4. Using the input element to define a command

An input element whose type attribute is in one of the Submit Button, Reset Button, Image Button, Button, Radio Button, or Checkbox states defines a command.

The Label of the command is determined as follows:

• If the type attribute is in one of the Submit Button, Reset Button, Image Button, or Button states, then the Label is the string given by the value attribute, if any, and a user agent-dependent, locale-dependent value that the user agent uses to label the button itself if the attribute is absent.
• Otherwise, if the element is a labeled control, then the Label is the string given by the textContent of the first label element in tree order whose labeled control is the element in question. (In DOM terms, this is the string given by element.labels[0].textContent.)
• Otherwise, if the value attribute is present, then the Label is the value of that attribute.
• Otherwise, the Label is the empty string.

The Access Key of the command is the element’s assigned access key, if any.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State of the command is true if the element or one of its ancestors is inert, or if the element’s disabled state is set, and false otherwise.

The Action of the command, if the element has a defined activation behavior, is to run synthetic click activation steps on the element. Otherwise, it is just to fire a click event at the element.

4.11.3.5. Using the option element to define a command

An option element with an ancestor select element and either no value attribute or a value attribute that is not the empty string defines a command.

The Label of the command is the value of the option element’s label attribute, if there is one, or else the value of option element’s textContent IDL attribute, with leading and trailing white space stripped, and with any sequences of two or more space characters replaced by a single U+0020 SPACE character.

The Access Key of the command is the element’s assigned access key, if any.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State of the command is true if the element is disabled, or if its nearest ancestor select element is disabled, or if it or one of its ancestors is inert, and false otherwise.

If the option’s nearest ancestor select element has a multiple attribute, the Action of the command is to pick the option element. Otherwise, the Action is to toggle the option element.

4.11.3.6. Using the accesskey attribute on a label element to define a command

A label element that has an assigned access key and a labeled control and whose labeled control defines a command, itself defines a command.

The Label of the command is the string given by the element’s textContent IDL attribute.

The Access Key of the command is the element’s assigned access key.

The Hidden State, Disabled State, and Action facets of the command are the same as the respective facets of the element’s labeled control.

4.11.3.7. Using the accesskey attribute on a legend element to define a command

A legend element that has an assigned access key and is a child of a fieldset element that has a descendant that is not a descendant of the legend element and is neither a label element nor a legend element but that defines a command, itself defines a command.

The Label of the command is the string given by the element’s textContent IDL attribute.

The Access Key of the command is the element’s assigned access key.

The Hidden State, Disabled State, and Action facets of the command are the same as the respective facets of the first element in tree order that is a descendant of the parent of the legend element that defines a command but is not a descendant of the legend element and is neither a label nor a legend element.

4.11.3.8. Using the accesskey attribute to define a command on other elements

An element that has an assigned access key defines a command.

If one of the earlier sections that define elements that define commands define that this element defines a command, then that section applies to this element, and this section does not. Otherwise, this section applies to that element.

The Label of the command depends on the element. If the element is a labeled control, the textContent of the first label element in tree order whose labeled control is the element in question is the Label (in DOM terms, this is the string given by element.labels[0].textContent). Otherwise, the Label is the textContent of the element itself.

The Access Key of the command is the element’s assigned access key.

The Hidden State of the command is true (hidden) if the element has a hidden attribute, and false otherwise.

The Disabled State of the command is true if the element or one of its ancestors is inert, and false otherwise.

The Action of the command is to run the following steps:

1. Run the focusing steps for the element.
2. If the element has a defined activation behavior, run synthetic click activation steps on the element.
3. Otherwise, if the element does not have a defined activation behavior, fire a click event at the element.

4.11.4. The dialog element

Categories:

Flow content.

Sectioning root.

Contexts in which this element can be used:

Where flow content is expected.

Content model:

Flow content.

Tag omission in text/html:

Neither tag is omissible

Content attributes:

Global attributes

open - Whether the dialog box is showing

Allowed ARIA role attribute values:

dialog (default - do not set) or alertdialog.

Allowed ARIA state and property attributes:

Global aria-* attributes

Any aria-* attributes applicable to the default or allowed roles.

DOM interface:

interface HTMLDialogElement : HTMLElement {
  attribute boolean open;
  attribute DOMString returnValue;
  void show(optional (MouseEvent or Element) anchor);
  void showModal(optional (MouseEvent or Element) anchor);
  void close(optional DOMString returnValue);
};

The dialog element represents a part of an application that a user interacts with to perform a task, for example a dialog box, inspector, or window.

The open attribute is a boolean attribute. When specified, it indicates that the dialog element is active and that the user can interact with it.

...
<body>
<div> <!-- body content --> </div>
<dialog>
  <h1>Add to Wallet</h1>
  <label for="num">How many gold coins do you want to add to your wallet?</label>
  <div><input name=amt id="num" type=number min=0 step=0.01 value=100></div>
  <p><strong>You add coins at your own risk.</strong></p>
  <div><label><input name=round type=checkbox> Only add perfectly round coins </label>
  <div><input type=button onclick="submit()" value="Add Coins"></div>
</dialog>
</body>
...

A dialog element without an open attribute specified should not be shown to the user. This requirement may be implemented indirectly through the style layer. For example, user agents that support the suggested default rendering implement this requirement using the CSS rules described in §10 Rendering.

The tabindex attribute must not be specified on dialog elements.

dialog . show( [ anchor ] )

Displays the dialog element.

The argument, if provided, provides an anchor point to which the element will be fixed.

dialog . showModal( [ anchor ] )

Displays the dialog element and makes it the top-most modal dialog.

The argument, if provided, provides an anchor point to which the element will be fixed.

This method honors the autofocus attribute.

dialog . close( [ result ] )

Closes the dialog element.

The argument, if provided, provides a return value.

dialog . returnValue [ = result ]

Returns the dialog’s return value.

Can be set, to update the return value.

When the show() method is invoked, the user agent must run the following steps:

1. If the element already has an open attribute, then abort these steps.
2. Add an open attribute to the dialog element, whose value is the empty string.
3. If the show() method was invoked with an argument, set up the position of the dialog element, using that argument as the anchor. Otherwise, set the dialog to the normal alignment mode.
4. Run the dialog focusing steps for the dialog element.

Each Document has a stack of dialog elements known as the pending dialog stack. When a Document is created, this stack must be initialized to be empty.

When an element is added to the pending dialog stack, it must also be added to the top layer. When an element is removed from the pending dialog stack, it must be removed from the top layer. [FULLSCREEN]

When the showModal() method is invoked, the user agent must run the following steps:

1. Let subject be the dialog element on which the method was invoked.
2. If subject already has an open attribute, then throw an InvalidStateError exception and abort these steps.
3. If subject is not in a Document, then throw an InvalidStateError exception and abort these steps.
4. Add an open attribute to subject, whose value is the empty string.
5. If the showModal() method was invoked with an argument, set up the position of subject, using that argument as the anchor. Otherwise, set the dialog to the centered alignment mode.
6. Let subject’s node document be blocked by the modal dialog subject.
7. Push subject onto subject’s node document’s pending dialog stack.
8. Run the dialog focusing steps for subject.

The dialog focusing steps for a dialog element subject are as follows:

1. If for some reason subject is not a control group owner at this point, or if it is inert, abort these steps.

2. Let control be the first non-inert focusable area in subject’s control group whose DOM anchor has an autofocus attribute specified.

   If there isn’t one, then let control be the first non-inert focusable area in subject’s control group.

   If there isn’t one of those either, then let control be subject.

3. Run the focusing steps for control.

If at any time a dialog element is removed from a Document, then if that dialog is in that Document’s pending dialog stack, the following steps must be run:

1. Let subject be that dialog element and document be the Document from which it is being removed.
2. Remove subject from document’s pending dialog stack.
3. If document’s pending dialog stack is not empty, then let document be blocked by the modal dialog that is at the top of document’s pending dialog stack. Otherwise, let document be no longer blocked by a modal dialog at all.

When the close() method is invoked, the user agent must close the dialog that the method was invoked on. If the method was invoked with an argument, that argument must be used as the return value; otherwise, there is no return value.

When a dialog element subject is to be closed, optionally with a return value result, the user agent must run the following steps:

1. If subject does not have an open attribute, then abort these steps.
2. Remove subject’s open attribute.
3. If the argument result was provided, then set the returnValue attribute to the value of result.

4. If subject is in its Document’s pending dialog stack, then run these substeps:

   1. Remove subject from that pending dialog stack.
   2. If that pending dialog stack is not empty, then let subject’s node document be blocked by the modal dialog that is at the top of the pending dialog stack. Otherwise, let document be no longer blocked by a modal dialog at all.
5. Queue a task to fire a simple event named close at subject.

The returnValue IDL attribute, on getting, must return the last value to which it was set. On setting, it must be set to the new value. When the element is created, it must be set to the empty string.

Canceling dialogs: When a Document’s pending dialog stack is not empty, user agents may provide a user interface that, upon activation, queues a task to fire a simple event named cancel that is cancelable at the top dialog element on the Document’s pending dialog stack. The default action of this event must be to check if that element has an open attribute, and if it does, close the dialog with no return value.

An example of such a UI mechanism would be the user pressing the "Escape" key.

All dialog elements are always in one of three modes: normal alignment, centered alignment, and magic alignment. When a dialog element is created, it must be placed in the normal alignment mode. In this mode, normal CSS requirements apply to the element. The centered alignment mode is only used for dialog elements that are in the top layer. [FULLSCREEN] [CSS-2015]

When an element subject is placed in centered alignment mode, and when it is in that mode and has new rendering boxes created, the user agent must set up the element such that its top static position, for the purposes of calculating the used value of the top property, is the value that would place the element’s top margin edge as far from the top of the viewport as the element’s bottom margin edge from the bottom of the viewport, if the element’s height is less than the height of the viewport, and otherwise is the value that would place the element’s top margin edge at the top of the viewport.

If there is a dialog element with centered alignment and that is being rendered when its browsing context changes viewport width (as measured in CSS pixels), then the user agent must recreate the element’s boxes, recalculating its top static position as in the previous paragraph.

This top static position of a dialog element with centered alignment must remain the element’s top static position until its boxes are recreated. (The element’s static position is only used in calculating the used value of the top property in certain situations; it’s not used, for instance, to position the element if its position property is set to static.)

When a user agent is to set up the position of an element subject using an anchor anchor, it must run the following steps:

1. If anchor is a MouseEvent object, then run these substeps:

   1. If anchor’s target element does not have a rendered box, or is in a different document than subject, then let subject be in the centered alignment mode, and abort the set up the position steps.
   2. Let anchor element be an anonymous element rendered as a box with zero height and width (so its margin and border boxes both just form a point), positioned so that its top and left are at the coordinate identified by the event, and whose properties all compute to their initial values.

   Otherwise, let anchor element be anchor.

2. Put subject in the magic alignment mode, aligned to anchor element.

While an element A has magic alignment, aligned to an element B, the following requirements apply:

• If at any time either A or B cease having rendered boxes, A and B cease being in the same Document, or B ceases being earlier than A in tree order, then, if subject is in the pending dialog stack, let subject’s mode become centered alignment, otherwise, let subject’s mode become normal alignment.

• A’s position property must compute to the keyword 'absolute-anchored' rather than whatever it would otherwise compute to (i.e., the position property’s specified value is ignored).

  The 'absolute-anchored' keyword’s requirements are described below.

• The anchor points for A and B are defined as per the appropriate entry in the following list:

  If the computed value of anchor-point is none on both A and B

  The anchor points of A and B are the center points of their respective first boxes' border boxes.

  If the computed value of anchor-point is none on A and a specific point on B

  The anchor point of B is the point given by its anchor-point property.

  If the anchor point of B is the center point of B’s first box’s border box, then A’s anchor point is the center point of its first box’s margin box.

  Otherwise, A’s anchor point is on one of its margin edges. Consider four hypothetical half-infinite lines L1, L2, L3, and L4 that each start in the center of B’s first box’s border box, and that extend respectively through the top left corner, top right corner, bottom right corner, and bottom left corner of B’s first box’s border box. A’s anchor point is determined by the location of B’s anchor point relative to these four hypothetical lines, as follows:

  If the anchor point of B lies on L1 or L2, or inside the area bounded by L1 and L2 that also contains the points above B’s first box’s border box, then let A’s anchor point be the horizontal center of A’s bottom margin edge.

  Otherwise, if the anchor point of B lies on L3 or L4, or inside the area bounded by L3 and L4 that also contains the points below B’s first box’s border box, then let A’s anchor point be the horizontal center of A’s top margin edge.

  Otherwise, if the anchor point of B lies inside the area bounded by L4 and L1 that also contains the points to the left of B’s first box’s border box, then let A’s anchor point be the vertical center of A’s right margin edge.

  Otherwise, the anchor point of B lies inside the area bounded by L2 and L3 that also contains the points to the right of B’s first box’s border box; let A’s anchor point be the vertical center of A’s left margin edge.

  If the computed value of anchor-point is a specific point on A and none on B

  The anchor point of A is the point given by its anchor-point property.

  If the anchor point of A is the center point of A’s first box’s margin box, then B’s anchor point is the center point of its first box’s border box.

  Otherwise, B’s anchor point is on one of its border edges. Consider four hypothetical half-infinite lines L1, L2, L3, and L4 that each start in the center of A’s first box’s margin box, and that extend respectively through the top left corner, top right corner, bottom right corner, and bottom left corner of A’s first box’s margin box. B’s anchor point is determined by the location of A’s anchor point relative to these four hypothetical lines, as follows:

  If the anchor point of A lies on L1 or L2, or inside the area bounded by L1 and L2 that also contains the points above A’s first box’s margin box, then let B’s anchor point be the horizontal center of B’s bottom border edge.

  Otherwise, if the anchor point of A lies on L3 or L4, or inside the area bounded by L3 and L4 that also contains the points below A’s first box’s margin box, then let B’s anchor point be the horizontal center of B’s top border edge.

  Otherwise, if the anchor point of A lies inside the area bounded by L4 and L1 that also contains the points to the left of A’s first box’s margin box, then let B’s anchor point be the vertical center of B’s right border edge.

  Otherwise, the anchor point of A lies inside the area bounded by L2 and L3 that also contains the points to the right of A’s first box’s margin box; let B’s anchor point be the vertical center of B’s left border edge.

  If the computed value of anchor-point is a specific point on both A and B

  The anchor points of A and B are the points given by their respective anchor-point properties.

  The rules above generally use A’s margin box, but B’s border box. This is because while A always has a margin box, and using the margin box allows for the dialog to be positioned offset from the box it is annotating, B sometimes does not have a margin box (e.g., if it is a table-cell), or has a margin box whose position may be not entirely clear (e.g., in the face of margin collapsing and clear handling of in-flow blocks).

  In cases where B does not have a border box but its border box is used by the algorithm above, user agents must use its first box’s content area instead. (This is in particular an issue with boxes in tables that have border-collapse set to collapse.)

• When an element’s position property computes to 'absolute-anchored', the float property does not apply and must compute to none, the display property must compute to a value as described by the table in the section of CSS 2.1 describing the relationships between display, position, and float, and the element’s box must be positioned using the rules for absolute positioning but with its static position set such that if the box is positioned in its static position, its anchor point is exactly aligned over the anchor point of the element to which it is magically aligned. Elements aligned in this way are absolutely positioned. For the purposes of determining the containing block of other elements, the 'absolute-anchored' keyword must be treated like the absolute keyword.

The trivial example of an element that does not have a rendered box is one whose display property computes to none. However, there are many other cases; e.g., table columns do not have boxes (their properties merely affect other boxes).

If an element to which another element is anchored changes rendering, the anchored element will be repositioned accordingly. (In other words, the requirements above are live, they are not just calculated once per anchored element.)

The 'absolute-anchored' keyword is not a keyword that can be specified in CSS; the position property can only compute to this value if the dialog element is positioned via the APIs described above.

User agents in visual interactive media should allow the user to pan the viewport to access all parts of a dialog element’s border box, even if the element is larger than the viewport and the viewport would otherwise not have a scroll mechanism (e.g., because the viewport’s overflow property is set to hidden).

The open IDL attribute must reflect the open content attribute.

4.11.4.1. Anchor points

This section will eventually be moved to a CSS specification; it is specified here only on an interim basis until an editor can be found to own this.

The anchor-point property specifies a point to which dialog boxes are to be aligned.

If the value is a <position>, the anchor point is the point given by the value, which must be interpreted relative to the element’s first rendered box’s margin box. Percentages must be calculated relative to the element’s first rendered box’s margin box (specifically, its width for the horizontal position and its height for the vertical position). [CSS-VALUES] [CSS-2015]

If the value is the keyword none, then no explicit anchor point is defined. The user agent will pick an anchor point automatically if necessary (as described in the definition of the open() method above).