HTML

Living Standard — Last Updated 7 March 2025

1. 1. 4.11 Interactive elements
      1. 4.11.1 The details element
      2. 4.11.2 The summary element
      3. 4.11.3 Commands
         1. 4.11.3.1 Facets
         2. 4.11.3.2 Using the a element to define a command
         3. 4.11.3.3 Using the button element to define a command
         4. 4.11.3.4 Using the input element to define a command
         5. 4.11.3.5 Using the option element to define a command
         6. 4.11.3.6 Using the accesskey attribute on a legend element to define a command
         7. 4.11.3.7 Using the accesskey attribute to define a command on other elements
      4. 4.11.4 The dialog element
      5. 4.11.5 Dialog light dismiss

4.11 Interactive elements

4.11.1 The details element

Categories :

Flow content .

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 .

Content attributes :

Global attributes

name

open

Accessibility considerations :

For authors .

For implementers .

DOM interface :

[Exposed=Window]
interface HTMLDetailsElement : HTMLElement {
  [HTMLConstructor] constructor();
  [CEReactions] attribute DOMString name;
  [CEReactions] attribute boolean open;
};

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

As with all HTML elements, it is not conforming to use the details element when attempting to represent another type of control. For example, tab widgets and menu widgets are not disclosure widgets, so abusing the details element to implement these patterns is incorrect.

The details element is not appropriate for footnotes. Please see the section on footnotes for details on how to mark up footnotes.

The first summary element child of the element, if any, represents the summary or legend of the details. If there is no child summary element, the user agent should provide its own legend (e.g. "Details").

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

The name content attribute gives the name of the group of related details elements that the element is a member of. Opening one member of this group causes other members of the group to close. If the attribute is specified, its value must not be the empty string.

Before using this feature, authors should consider whether this grouping of related details elements into an exclusive accordion is helpful or harmful to users. While using an exclusive accordion can reduce the maximum amount of space that a set of content can occupy, it can also frustrate users who have to open many items to find what they want or users who want to look at the contents of multiple items at the same time.

A document must not contain more than one details element in the same details name group that has the open attribute present. Authors must not use script to add details elements to a document in a way that would cause a details name group to have more than one details element with the open attribute present.

The group of elements that is created by a common name attribute is exclusive, meaning that at most one of the details elements can be open at once. While this exclusivity is enforced by user agents, the resulting enforcement immediately changes the open attributes in the markup. This requirement on authors forbids such misleading markup.

A document must not contain a details element that is a descendant of another details element in the same details name group .

Documents that use the name attribute to group multiple related details elements should keep those related elements together in a containing element (such as a section element or article element). When it makes sense for the group to be introduced with a heading, authors should put that heading in a heading element at the start of the containing element.

Visually and programmatically grouping related elements together can be important for accessible user experiences. This can help users understand the relationship between such elements. When related elements are in disparate sections of a web page rather than being grouped, the elements' relationships to each other can be less discoverable or understandable.

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.

The details name group that contains a details element a also contains all the other details elements b that fulfill all of the following conditions:

• Both a and b are in the same tree .
• They both have a name attribute, their name attributes are not the empty string, and the value of a 's name attribute equals the value of b 's name attribute.

Every details element has a details toggle task tracker , which is a toggle task tracker or null, initially null.

The following attribute change steps , given element , localName , oldValue , value , and namespace , are used for all details elements:

1. If namespace is not null, then return.

2. If localName is name , then ensure details exclusivity by closing the given element if needed given element .

3. If localName is open , then:

   1. If one of oldValue or value is null and the other is not null, run the following steps, which are known as the details notification task steps , for this details element:

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

      1. If oldValue is null, queue a details toggle event task given the details element, " closed ", and " open ".

      2. Otherwise, queue a details toggle event task given the details element, " open ", and " closed ".

   2. If oldValue is null and value is not null, then ensure details exclusivity by closing other elements if needed given element .

The details HTML element insertion steps , given insertedNode , are:

1. Ensure details exclusivity by closing the given element if needed given insertedNode .

To be clear, these attribute change and insertion steps also run when an attribute or element is inserted via the parser.

To queue a details toggle event task given a details element element , a string oldState , and a string newState :

1. If element 's details toggle task tracker is not null, then:

   1. Set oldState to element 's details toggle task tracker 's old state .

   2. Remove element 's details toggle task tracker 's task from its task queue .

   3. Set element 's details toggle task tracker to null.

2. Queue an element task given the DOM manipulation task source and element to run the following steps:

   1. Fire an event named toggle at element , using ToggleEvent , with the oldState attribute initialized to oldState and the newState attribute initialized to newState .

   2. Set element 's details toggle task tracker to null.

3. Set element 's details toggle task tracker to a struct with task set to the just-queued task and old state set to oldState .

To ensure details exclusivity by closing other elements if needed given a details element element :

1. Assert : element has an open attribute.

2. If element does not have a name attribute, or its name attribute is the empty string, then return.

3. Let groupMembers be a list of elements, containing all elements in element 's details name group except for element , in tree order .

4. For each element otherElement of groupMembers :

   1. If the open attribute is set on otherElement , then:

      1. Assert : otherElement is the only element in groupMembers that has the open attribute set.

      2. Remove the open attribute on otherElement .

      3. Break .

To ensure details exclusivity by closing the given element if needed given a details element element :

1. If element does not have an open attribute, then return.

2. If element does not have a name attribute, or its name attribute is the empty string, then return.

3. Let groupMembers be a list of elements, containing all elements in element 's details name group except for element , in tree order .

4. For each element otherElement of groupMembers :

   1. If the open attribute is set on otherElement , then:

      1. Remove the open attribute on element .

      2. Break .

The name and open IDL attributes must reflect the respective content attributes of the same name.

The ancestor details revealing algorithm is to run the following steps on currentNode :

1. While currentNode has a parent node within the flat tree :

   1. If currentNode is slotted into the second slot of a details element:

      1. Set currentNode to the details element which currentNode is slotted into.

      2. If the open attribute is not set on currentNode , then set the open attribute on currentNode to the empty string.

   2. Otherwise, set currentNode to the parent node of currentNode within the flat tree .

<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>

<section class="characteristics">
 <details name="frame-characteristics">
  <summary>Material</summary>
  The picture frame is made of solid oak wood.
 </details>
 <details name="frame-characteristics">
  <summary>Size</summary>
  The picture frame fits a photo 40cm tall and 30cm wide.
  The frame is 45cm tall, 35cm wide, and 2cm thick.
 </details>
 <details name="frame-characteristics">
  <summary>Color</summary>
  The picture frame is available in its natural wood
  color, or with black stain.
 </details>
</section>

<section class="characteristics">
 <details name="frame-characteristics" id="d1" open>...</details>
 <details name="frame-characteristics" id="d2">...</details>
 <details name="frame-characteristics" id="d3">...</details>
</section>

document.getElementById("d2").setAttribute("open",
"");

<section class="characteristics">
 <details name="frame-characteristics" id="d1">...</details>
 <details name="frame-characteristics" id="d2" open>...</details>
 <details name="frame-characteristics" id="d3">...</details>
</section>

<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 :

Phrasing content , optionally intermixed with heading content .

Content attributes :

Global attributes

Accessibility considerations :

For authors .

For implementers .

DOM interface :

Uses HTMLElement .

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

A summary element is a summary for its parent details if the following algorithm returns true:

1. If this summary element has no parent, then return false.

2. Let parent be this summary element's parent.

3. If parent is not a details element, then return false.

4. If parent 's first summary element child is not this summary element, then return false.

5. Return true.

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

1. If this summary element is not the summary for its parent details , then return.

2. Let parent be this summary element's parent.

3. 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 menu items, 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 (basically, whether it should be shown in menus).

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 with a non-null 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.

For example, such commands could be listed in the user agent's menu bar.

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 element's descendant text content .

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 is 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 UA-dependent, locale-dependent value that the UA uses to label the button itself if the attribute is absent.

• Otherwise, if the element is a labeled control , then the Label is the descendant text content of the first label element in tree order whose labeled control is the element in question. (In JavaScript terms, this is 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 is 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 option element's descendant text content , with ASCII whitespace stripped and collapsed .

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 toggle the option element. Otherwise, the Action is to pick the option element.

4.11.3.6 Using the accesskey attribute on a legend element to define a command

A legend element defines a command if all of the following are true:

• It has an assigned access key .

• It is a child of a fieldset element.

• Its parent has a descendant that defines a command that is neither a label element nor a legend element. This element, if it exists, is the legend element's accesskey delegatee .

The Label of the command is the element's descendant text content .

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 legend element's accesskey delegatee .

<fieldset>
 <legend accesskey=p>
  <label>I want <input name=pizza type=number step=1 value=1 min=0>
   pizza(s) with these toppings</label>
 </legend>
 <label><input name=pizza-cheese type=checkbox checked> Cheese</label>
 <label><input name=pizza-ham type=checkbox checked> Ham</label>
 <label><input name=pizza-pineapple type=checkbox> Pineapple</label>
</fieldset>

4.11.3.7 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 descendant text content of the first label element in tree order whose labeled control is the element in question is the Label (in JavaScript terms, this is given by element .labels[0].textContent ). Otherwise, the Label is the element's descendant text content .

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. Fire a click event at the element.

4.11.4 The dialog element

Categories :

Flow content .

Contexts in which this element can be used :

Where flow content is expected.

Content model :

Flow content .

Content attributes :

Global attributes

closedby

open

Accessibility considerations :

For authors .

For implementers .

DOM interface :

[Exposed=Window]
interface HTMLDialogElement : HTMLElement {
  [HTMLConstructor] constructor();
  [CEReactions] attribute boolean open;
  attribute DOMString returnValue;
  [CEReactions] attribute DOMString closedBy;
  [CEReactions] undefined show();
  [CEReactions] undefined showModal();
  [CEReactions] undefined close(optional DOMString returnValue);
  [CEReactions] undefined requestClose(optional DOMString returnValue);
};

The dialog element represents a transitory part of an application, in the form of a small window ("dialog box"), which the user interacts with to perform a task or gather information. Once the user is done, the dialog can be automatically closed by the application, or manually closed by the user.

Especially for modal dialogs, which are a familiar pattern across all types of applications, authors should work to ensure that dialogs in their web applications behave in a way that is familiar to users of non-web applications.

As with all HTML elements, it is not conforming to use the dialog element when attempting to represent another type of control. For example, context menus, tooltips, and popup listboxes are not dialog boxes, so abusing the dialog element to implement these patterns is incorrect.

An important part of user-facing dialog behavior is the placement of initial focus. The dialog focusing steps attempt to pick a good candidate for initial focus when a dialog is shown, but might not be a substitute for authors carefully thinking through the correct choice to match user expectations for a specific dialog. As such, authors should use the autofocus attribute on the descendant element of the dialog that the user is expected to immediately interact with after the dialog opens. If there is no such element, then authors should use the autofocus attribute on the dialog element itself.

<dialog>
  <label>Product Number <input type="text" readonly></label>
  <label>Product Name <input type="text" autofocus></label>
</dialog>

Another important aspect of user behavior is whether dialogs are scrollable or not. In some cases, overflow (and thus scrollability) cannot be avoided, e.g., when it is caused by the user's high text zoom settings. But in general, scrollable dialogs are not expected by users. Adding large text nodes directly to dialog elements is particularly bad as this is likely to cause the dialog element itself to overflow. Authors are best off avoiding them.

<dialog style="height: 80vh;">
  <div style="overflow: auto; height: 60vh;" autofocus>
    <p>By placing an order via this Web site on the first day of the fourth month of the year
    2010 Anno Domini, you agree to grant Us a non-transferable option to claim, for now and for
    ever more, your immortal soul.</p>
    <p>Should We wish to exercise this option, you agree to surrender your immortal soul,
    and any claim you may have on it, within 5 (five) working days of receiving written
    notification from  this site or one of its duly authorized minions.</p>
    <!-- ... etc., with many more <p> elements ... -->
  </div>
  <form method="dialog">
    <button type="submit" value="agree">Agree</button>
    <button type="submit" value="disagree">Disagree</button>
  </form>
</dialog>

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

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.

The closedby content attribute is an enumerated attribute with the following keywords and states:

The closedby attribute's invalid value default and missing value default are both the Auto state.

The Auto state behaves as Close Request state when the dialog was shown using its showModal() method; otherwise the None state.

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 the Rendering section .

The tabindex attribute must not be specified on dialog elements.

dialog . show ()

✔ MDN

HTMLDialogElement/show

Support in all current engines.

Firefox 98+ Safari 15.4+ Chrome 37+

---

Opera ? Edge 79+

---

Edge (Legacy) ? Internet Explorer No

---

Firefox Android ? Safari iOS ? Chrome Android ? WebView Android ? Samsung Internet ? Opera Android ?

Displays the dialog element.

dialog . showModal ()

✔ MDN

HTMLDialogElement/showModal

Support in all current engines.

Firefox 98+ Safari 15.4+ Chrome 37+

---

Opera ? Edge 79+

---

Edge (Legacy) ? Internet Explorer No

---

Firefox Android ? Safari iOS ? Chrome Android ? WebView Android ? Samsung Internet ? Opera Android ?

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

This method honors the autofocus attribute.

dialog . close ([ result ])

✔ MDN

HTMLDialogElement/close

Support in all current engines.

Firefox 98+ Safari 15.4+ Chrome 37+

---

Opera ? Edge 79+

---

Edge (Legacy) ? Internet Explorer No

---

Firefox Android ? Safari iOS ? Chrome Android ? WebView Android ? Samsung Internet ? Opera Android ?

Closes the dialog element.

The argument, if provided, provides a return value.

dialog . requestClose ([ result ])

Acts as if a close request was sent targeting dialog , by first firing a cancel event, and if that event is not canceled with preventDefault() , proceeding to close the dialog in the same way as the close() method (including firing a close event).

This is a helper utility that can be used to consolidate cancelation and closing logic into the cancel and close event handlers, by having all non- close request closing affordances call this method.

Note that this method ignores the closedby attribute: that is, even if closedby is set to " none ", the same behavior will apply.

The argument, if provided, provides a return value.

dialog . returnValue [ = result ]

✔ MDN

HTMLDialogElement/returnValue

Support in all current engines.

Firefox 98+ Safari 15.4+ Chrome 37+

---

Opera ? Edge 79+

---

Edge (Legacy) ? Internet Explorer No

---

Firefox Android ? Safari iOS ? Chrome Android ? WebView Android ? Samsung Internet ? Opera Android ?

Returns the dialog 's return value.

Can be set, to update the return value.

The show() method steps are:

1. If this has an open attribute and is modal of this is false, then return.

2. If this has an open attribute, then throw an " InvalidStateError " DOMException .

3. If the result of firing an event named beforetoggle , using ToggleEvent , with the cancelable attribute initialized to true, the oldState attribute initialized to " closed ", and the newState attribute initialized to " open " at this is false, then return.

4. If this has an open attribute, then return.

5. Queue a dialog toggle event task given this , " closed ", and " open ".

6. Add an open attribute to this , whose value is the empty string.

7. Assert : this 's node document 's open dialogs list does not contain this .

8. Add this to this 's node document 's open dialogs list .

9. Set the dialog close watcher with this .

10. Set this 's previously focused element to the focused element.

11. Let document be this 's node document .

12. Let hideUntil be the result of running topmost popover ancestor given this , document 's showing hint popover list , null, and false.

13. If hideUntil is null, then set hideUntil to the result of running topmost popover ancestor given this , document 's showing auto popover list , null, and false.

14. If hideUntil is null, then set hideUntil to document .

15. Run hide all popovers until given hideUntil , false, and true.

16. Run the dialog focusing steps given this .

The showModal() method steps are to show a modal dialog given this .

The close( returnValue ) method steps are:

1. If returnValue is not given, then set it to null.

2. Close the dialog this with returnValue .

The requestClose( returnValue ) method steps are:

1. If this does not have an open attribute, then return.

2. Assert : this 's close watcher is not null.

3. Set dialog 's enable close watcher for requestClose() to true.

4. If returnValue is not given, then set it to null.

5. Set this 's request close return value to returnValue .

6. Request to close dialog 's close watcher with false.

7. Set dialog 's enable close watcher for requestClose() to false.

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.

The closedBy getter steps are to return the keyword corresponding to the computed closed-by state given this .

The closedBy setter steps are to set the closedby content attribute to the given value.

The open IDL attribute must reflect the open content attribute.

Each Document has a dialog pointerdown target , which is an HTML dialog element or null, initially null.

Each HTML element has a previously focused element which is null or an element, and it is initially null. When showModal() and show() are called, this element is set to the currently focused element before running the dialog focusing steps . Elements with the popover attribute set this element to the currently focused element during the show popover algorithm .

Each dialog element has a dialog toggle task tracker , which is a toggle task tracker or null, initially null.

Each dialog element has a close watcher , which is a close watcher or null, initially null.

Each dialog element has a request close return value , which is a string, initially null.

Each dialog element has an enable close watcher for requestClose() boolean, initially false.

Each dialog element has an is modal boolean, initially false.

The dialog HTML element removing steps , given removedNode and oldParent , are:

1. If removedNode 's close watcher is not null, then:

   1. Destroy removedNode 's close watcher .

   2. Set removedNode 's close watcher to null.

2. If removedNode 's node document 's top layer contains removedNode , then remove an element from the top layer immediately given removedNode .

3. Set is modal of removedNode to false.

4. Remove removedNode from removedNode 's node document 's open dialogs list .

To show a modal dialog given a dialog element subject :

1. If subject has an open attribute and is modal of subject is true, then return.

2. If subject has an open attribute, then throw an " InvalidStateError " DOMException .

3. If subject 's node document is not fully active , then throw an " InvalidStateError " DOMException .

4. If subject is not connected , then throw an " InvalidStateError " DOMException .

5. If subject is in the popover showing state , then throw an " InvalidStateError " DOMException .

6. If the result of firing an event named beforetoggle , using ToggleEvent , with the cancelable attribute initialized to true, the oldState attribute initialized to " closed ", and the newState attribute initialized to " open " at subject is false, then return.

7. If subject has an open attribute, then return.

8. If subject is not connected , then return.

9. If subject is in the popover showing state , then return.

10. Queue a dialog toggle event task given subject , " closed ", and " open ".

11. Add an open attribute to subject , whose value is the empty string.

12. Set is modal of subject to true.

13. Assert : subject 's node document 's open dialogs list does not contain subject .

14. Add subject to subject 's node document 's open dialogs list . Let subject 's node document be blocked by the modal dialog subject .

    This will cause the focused area of the document to become inert (unless that currently focused area is a shadow-including descendant of subject ). In such cases, the focused area of the document will soon be reset to the viewport . In a couple steps we will attempt to find a better candidate to focus.

15. If subject 's node document 's top layer does not already contain subject , then add an element to the top layer given subject .

16. Set the dialog close watcher with subject .

17. Set subject 's previously focused element to the focused element.

18. Let document be subject 's node document .

19. Let hideUntil be the result of running topmost popover ancestor given subject , document 's showing hint popover list , null, and false.

20. If hideUntil is null, then set hideUntil to the result of running topmost popover ancestor given subject , document 's showing auto popover list , null, and false.

21. If hideUntil is null, then set hideUntil to document .

22. Run hide all popovers until given hideUntil , false, and true.

23. Run the dialog focusing steps given subject .

To set the dialog close watcher , given a dialog element dialog :

1. Set dialog 's close watcher to the result of establishing a close watcher given dialog 's relevant global object , with:

   • cancelAction given canPreventClose being to return the result of firing an event named cancel at dialog , with the cancelable attribute initialized to canPreventClose .

   • closeAction being to close the dialog given dialog and dialog 's request close return value .

   • getEnabledState being to return true if dialog 's enable close watcher for requestClose() is true or dialog 's computed closed-by state is not None ; otherwise false.

The is valid invoker command steps for dialog elements, given a command attribute command , are:

1. If command is in the Close state or in the Show Modal state, then return true.

2. Return false.

The invoker command steps for dialog elements, given an element element , an element invoker , and a command attribute command , are:

1. If element is in the popover showing state, then return.

2. If command is in the Close state and element has an open attribute:

   1. Let value be invoker 's value .

   2. Close the dialog element with value .

3. If command is the Show Modal state and element does not have an open attribute, then show a modal dialog given element .

<button type=button
        commandfor="the-dialog"
        command="show-modal">
 Delete
</button>
<dialog id="the-dialog">
 <form action="/delete" method="POST">
  <button type="submit">
   Delete
  </button>
  <button commandfor="the-dialog"
          command="close">
   Cancel
  </button>
 </form>
</dialog>

When a dialog element subject is to be closed , with null or a string result , run these steps:

1. If subject does not have an open attribute, then return.

2. Fire an event named beforetoggle , using ToggleEvent , with the oldState attribute initialized to " open " and the newState attribute initialized to " closed " at subject .

3. If subject does not have an open attribute, then return.

4. Queue a dialog toggle event task given subject , " open ", and " closed ".

5. Remove subject 's open attribute.

6. If is modal of subject is true, then request an element to be removed from the top layer given subject .

7. Let wasModal be the value of subject 's is modal flag.

8. Set is modal of subject to false.

9. Remove subject from subject 's node document 's open dialogs list .

10. If result is not null, then set the returnValue attribute to result .

11. Set the request close return value to null.

12. If subject 's previously focused element is not null, then:

    1. Let element be subject 's previously focused element .

    2. Set subject 's previously focused element to null.

    3. If subject 's node document 's focused area of the document 's DOM anchor is a shadow-including inclusive descendant of subject , or wasModal is true, then run the focusing steps for element ; the viewport should not be scrolled by doing this step.

13. Queue an element task on the user interaction task source given the subject element to fire an event named close at subject .

14. If subject 's close watcher is not null, then:

    1. Destroy subject 's close watcher .

    2. Set subject 's close watcher to null.

To queue a dialog toggle event task given a dialog element element , a string oldState , and a string newState :

1. If element 's dialog toggle task tracker is not null, then:

   1. Set oldState to element 's dialog toggle task tracker 's old state .

   2. Remove element 's dialog toggle task tracker 's task from its task queue .

   3. Set element 's dialog toggle task tracker to null.

2. Queue an element task given the DOM manipulation task source and element to run the following steps:

   1. Fire an event named toggle at element , using ToggleEvent , with the oldState attribute initialized to oldState and the newState attribute initialized to newState .

   2. Set element 's dialog toggle task tracker to null.

3. Set element 's dialog toggle task tracker to a struct with task set to the just-queued task and old state set to oldState .

To retrieve a dialog's computed closed-by state , given a dialog dialog :

1. If the state of dialog 's closedby attribute is Auto :

   1. If dialog 's is modal is true, then return Close Request .

   2. Return None .

2. Return the state of dialog 's closedby attribute.

The dialog focusing steps , given a dialog element subject , are as follows:

1. If the allow focus steps given subject 's node document return false, then return.

2. Let control be null.

3. If subject has the autofocus attribute, then set control to subject .

4. If control is null, then set control to the focus delegate of subject .

5. If control is null, then set control to subject .

6. Run the focusing steps for control .

   If control is not focusable , this will do nothing. This would only happen if subject had no focus delegate, and the user agent decided that dialog elements were not generally focusable. In that case, any earlier modifications to the focused area of the document will apply.

7. Let topDocument be control 's node navigable 's top-level traversable 's active document .

8. If control 's node document 's origin is not the same as the origin of topDocument , then return.

9. Empty topDocument 's autofocus candidates .

10. Set topDocument 's autofocus processed flag to true.

4.11.5 Dialog light dismiss

"Light dismiss" means that clicking outside of a dialog element whose closedby attribute is in the Any state will close the dialog element. This is in addition to how such dialog s respond to close requests .

To light dismiss open dialogs , given a PointerEvent event :

1. Assert : event 's isTrusted attribute is true.

2. Let document be event 's target 's node document .

3. If document 's open dialogs list is empty , then return.

4. Let ancestor be the result of running nearest clicked dialog given event .

5. If event 's type is " pointerdown ", then set document 's dialog pointerdown target to ancestor .

6. If event 's type is " pointerup ", then:

   1. Let sameTarget be true if ancestor is document 's dialog pointerdown target .

   2. Set document 's dialog pointerdown target to null.

   3. If sameTarget is false, then return.

   4. Let topmostDialog be the last element of document 's open dialogs list .

   5. If ancestor is topmostDialog , then return.

   6. If topmostDialog 's computed closed-by state is not Any , then return.

   7. Assert : topmostDialog 's close watcher is not null.

   8. Request to close topmostDialog 's close watcher with false.

To run light dismiss activities , given a PointerEvent event :

1. Run light dismiss open popovers with event .

2. Run light dismiss open dialogs with event .

Run light dismiss activities will be called by the Pointer Events spec when the user clicks or touches anywhere on the page.

To find the nearest clicked dialog , given a PointerEvent event :

1. Let target be event 's target .

2. If target is a dialog element, target has an open attribute, target 's is modal is true, and event 's clientX and clientY are outside the bounds of target , then return null.

   The check for clientX and clientY is because a pointer event that hits the ::backdrop pseudo element of a dialog will result in event having a target of the dialog element itself.

3. Let currentNode be target .

4. While currentNode is not null:

   1. If currentNode is a dialog element and currentNode has an open attribute, then return currentNode .

   2. Set currentNode to currentNode 's parent in the flat tree .

5. Return null.