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
      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 AndroidYesWebView Android?Samsung Internet?Opera Android14+
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
open — Whether the details are visible
Accessibility considerations:
For authors.
For implementers.
DOM interface:
Uses HTMLDetailsElement.

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 summary element child of the element, if any, represents the summary or legend of the details.

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.

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.

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 iOSYesChrome AndroidYesWebView Android4+Samsung Internet?Opera Android14+
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.

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.

4.11.4 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?
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:
Uses HTMLDialogElement.

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.

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()

Displays the dialog element.

dialog.showModal()

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

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.

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.

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>