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

4.11 Interactive elements

4.11.1 The details element

Element/details

Support in all current engines.

Firefox49+Safari6+Chrome12+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android49+Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

HTMLDetailsElement

Support in all current engines.

Firefox49+Safari6+Chrome10+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android37+Samsung Internet?Opera Android?
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.
Tag omission in text/html:
Neither tag is omissible.
Content attributes:
Global attributes
name — Name of group of mutually-exclusive details elements
open — Whether the details are visible
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.

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.

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.

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).

Keeping related elements together can be important for accessibility.

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:

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 document be element's node document.

  4. Let oldFlag be the value of document's fire mutation events flag.

  5. Set document's fire mutation events flag to false.

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

  7. 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.

  8. Set document's fire mutation events flag to oldFlag.

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 document be element's node document.

  4. Let oldFlag be the value of document's fire mutation events flag.

  5. Set document's fire mutation events flag to false.

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

  7. 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.

  8. Set document's fire mutation events flag to oldFlag.

HTMLDetailsElement/open

Support in all current engines.

Firefox49+Safari6+Chrome10+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android37+Samsung Internet?Opera Android?

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.

The following example shows the details element being used to hide technical details in a progress report.

<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>

The following shows how a details element can be used to hide some controls by default:

<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>

One could use this in conjunction with other details in a list to allow the user to collapse a set of fields down to a small set of headings, with the ability to open each one.

In these examples, the summary really just summarizes what the controls can change, and not the actual values, which is less than ideal.

The following example shows the name attribute of the details element being used to create an exclusive accordion, a set of details elements where a user action to open one details element causes any open details to close.

<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>

The following example shows what happens when the open attribute is set on a details element that is part of a set of elements using the name attribute to create an exclusive accordion.

Given the initial markup:

<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>

and the script:

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

then the resulting tree after the script executes will be equivalent to the markup:

<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>

because setting the open attribute on d2 removes it from d1.

The same happens when the user activates the summary element inside of d2.

Because the open attribute is added and removed automatically as the user interacts with the control, it can be used in CSS to style the element differently based on its state. Here, a style sheet is used to animate the color of the summary when the element is opened or closed:

<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

Element/summary

Support in all current engines.

Firefox49+Safari6+Chrome12+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android4+Samsung Internet?Opera Android?
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.
Tag omission in text/html:
Neither tag is omissible.
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:

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:

Even though the value attribute on input elements in the Image Button state is non-conformant, the attribute can still contribute to the Label determination, if it is present and the Image Button's alt attribute is missing.

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:

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.

In this example, the legend element specifies an accesskey, which, when activated, will delegate to the input element inside the legend element.

<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

Element/dialog

Support in all current engines.

Firefox98+Safari15.4+Chrome37+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

HTMLDialogElement

Support in all current engines.

Firefox98+Safari15.4+Chrome37+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?
Categories:
Flow content.
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
Accessibility considerations:
For authors.
For implementers.
DOM interface:
[Exposed=Window]
interface HTMLDialogElement : HTMLElement {
  [HTMLConstructor] constructor();

  [CEReactions] attribute boolean open;
  attribute DOMString returnValue;
  [CEReactions] undefined show();
  [CEReactions] undefined showModal();
  [CEReactions] undefined close(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.

In the following example, a dialog is used for editing the details of a product in an inventory management web application.

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

If the autofocus attribute was not present, the Product Number field would have been focused by the dialog focusing steps. Although that is reasonable behavior, the author determined that the more relevant field to focus was the Product Name field, as the Product Number field is readonly and expects no user input. So, the author used autofocus to override the default.

Even if the author wants to focus the Product Number field by default, they are best off explicitly specifying that by using autofocus on that input element. This makes the intent obvious to future readers of the code, and ensures the code stays robust in the face of future updates. (For example, if another developer added a close button, and positioned it in the node tree before the Product Number field).

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.

The following terms of service dialog respects the above suggestions.

<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>

Note how the dialog focusing steps would have picked the scrollable div element by default, but similarly to the previous example, we have placed autofocus on the div so as to be more explicit and robust against future changes.

In contrast, if the p elements expressing the terms of service did not have such a wrapper div element, then the dialog itself would become scrollable, violating the above advice. Furthermore, in the absence of any autofocus attribute, such a markup pattern would have violated the above advice and tripped up the dialog focusing steps's default behavior, and caused focus to jump to the Agree button, which is a bad user experience.

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.

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.

Removing the open attribute will usually hide the dialog. However, doing so has a number of strange additional consequences:

For these reasons, it is generally better to never remove the open attribute manually. Instead, use the close() method to close the dialog, or the hidden attribute to hide it.

The tabindex attribute must not be specified on dialog elements.

dialog.show()

HTMLDialogElement/show

Support in all current engines.

Firefox98+Safari15.4+Chrome37+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

Displays the dialog element.

dialog.showModal()

HTMLDialogElement/showModal

Support in all current engines.

Firefox98+Safari15.4+Chrome37+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
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 ])

HTMLDialogElement/close

Support in all current engines.

Firefox98+Safari15.4+Chrome37+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
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.returnValue [ = result ]

HTMLDialogElement/returnValue

Support in all current engines.

Firefox98+Safari15.4+Chrome37+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
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 the is modal flag of this is false, then return.

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

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

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

  5. Run hide all popovers given this's node document.

  6. Run the dialog focusing steps given this.

The showModal() method steps are:

  1. If this has an open attribute and the is modal flag of this is true, then return.

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

  3. If this is not connected, then throw an "InvalidStateError" DOMException.

  4. If this is in the popover showing state, then throw an "InvalidStateError" DOMException.

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

  6. Set the is modal flag of this to true.

  7. Let this's node document be blocked by the modal dialog this.

    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.

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

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

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

  11. Run hide all popovers given this's node document.

  12. Run the dialog focusing steps given this.

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

  1. Let control be null.

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

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

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

  5. 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.

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

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

  8. Empty topDocument's autofocus candidates.

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

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.

The close(returnValue) method steps are:

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

  2. Close the dialog this with returnValue.

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. Remove subject's open attribute.

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

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

  5. Set the is modal flag of subject to false.

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

  7. 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 element, or wasModal is true, then run the focusing steps for element; the viewport should not be scrolled by doing this step.

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

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

    1. Destroy subject's close watcher.

    2. Set subject's close watcher to null.

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.

We use show/close as the verbs for dialog elements, as opposed to verb pairs that are more commonly thought of as antonyms such as show/hide or open/close, due to the following constraints:

Furthermore, a survey of many other UI frameworks contemporary to the original design of the dialog element made it clear that the show/close verb pair was reasonably common.

In summary, it turns out that the implications of certain verbs, and how they are used in technology contexts, mean that paired actions such as showing and closing a dialog are not always expressible as antonyms.


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

Each dialog element has an is modal flag. When a dialog element is created, this flag must be set to false.

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.


HTMLDialogElement/open

Support in all current engines.

Firefox98+Safari15.4+Chrome37+
Opera?Edge79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

The open IDL attribute must reflect the open content attribute.

This dialog box has some small print. The strong element is used to draw the user's attention to the more important part.

<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>