Using the Popover API

Creating declarative popovers

In its simplest form, a popover is created by adding the popover attribute to the element that you want to contain your popover content. An id is also needed to associate the popover with its controls.

<div id="mypopover" popover>Popover content</div>

Adding this attribute causes the element to be hidden on page load by having display: none set on it. To show/hide the popover, you need to add at least one control button (also know as the popover invoker). You can set a <button> (or <input> of type="button") as a popover control button by giving it a popovertarget attribute, the value of which should be the ID of the popover to control:

<button popovertarget="mypopover">Toggle the popover</button>
<div id="mypopover" popover>Popover content</div>

The default behavior is for the button to be a toggle button — pressing it repeatedly will toggle the popover between showing and hidden.

If you want to change that behavior, you can use the popovertargetaction attribute — this takes a value of "hide", "show", or "toggle". For example, to create separate show and hide buttons, you could do this:

<button popovertarget="mypopover" popovertargetaction="show">
  Show popover
</button>
<button popovertarget="mypopover" popovertargetaction="hide">
  Hide popover
</button>
<div id="mypopover" popover>Popover content</div>

You can see how the previous code snippet renders in our Basic declarative popover example (source).

When a popover is shown, it has display: none removed from it and it is put into the top layer so it will sit on top of all other page content.

command and commandfor

The commandfor and command attributes provide very similar functionality to popovertarget and popovertargetaction, but with a more general design aimed at providing other functionality beyond popover commands, including custom commands.

The previous code snippet could be rewritten like this:

<button commandfor="mypopover" command="show-popover">Show popover</button>
<button commandfor="mypopover" command="hide-popover">Hide popover</button>
<div id="mypopover" popover>Popover content</div>

auto state, and "light dismiss"

When a popover element is set with popover or popover="auto" as shown above, it is said to have auto state. The two important behaviors to note about auto state are:

• The popover can be "light dismissed" — this means that you can hide the popover by clicking outside it.
• The popover can also be closed, using browser-specific mechanisms such as pressing the Esc key.
• Usually, only one auto popover can be shown at a time — showing a second popover when one is already shown will hide the first one. The exception to this rule is when you have nested auto popovers. See the Nested popovers section for more details.

Auto state is useful when you only want to show a single popover at once. Perhaps you have multiple teaching UI messages that you want to show, but don't want the display to start getting cluttered and confusing, or perhaps you are showing status messages where the new status overrides any previous status.

You can see the behavior described above in action in our Multiple auto popovers example (source). Try light dismissing the popovers after they are shown, and see what happens when you try to show both at the same time.

Popover accessibility features

When a relationship is established between a popover and its control (invoker) via the popovertarget attribute, the API automatically makes two other changes to the environment to allow keyboard and assistive technology (AT) users to more easily interact with the popover:

• When the popover is shown, the keyboard focus navigation order is updated so that the popover is next in the sequence: for example, when a button is pressed to show a popover, any buttons inside the popover will be next in the tabbing order (will be focused by pressing the Tab key). Conversely, when closing the popover via the keyboard (usually via the Esc key), focus is shifted back to the invoker.
• To allow AT such as screen readers to make sense of the relationship between the invoker and the popover, an implicit aria-details and aria-expanded relationship is set up between them.

Setting up a relationship between a popover and its control in this manner also creates an implicit anchor reference between the two — see Popover anchor positioning for more details.

Other ways to set up a popover-invoker relationship

You can set up a popover-invoker relationship in other ways, in addition to using the popovertarget attribute:

• Using the source option of the HTMLElement.showPopover() or HTMLElement.togglePopover() methods. Bear in mind that in this case, only the focus navigation order changes are made, not the implicit ARIA relationship. This because the source option can be set to any kind of element, not just <button> elements, and it cannot be guaranteed that the relationship would make sense.
• Between a <select> element and its dropdown picker, when opting it into customizable select element functionality via the appearance property base-select value. In this case, an implicit popover-invoker relationship is created between the two.

Using manual popover state

One alternative to auto state is manual state, achieved by setting popover="manual" on your popover element:

<div id="mypopover" popover="manual">Popover content</div>

In this state:

• The popover cannot be "light dismissed", although declarative show/hide/toggle buttons (as seen earlier) will still work.
• Multiple independent popovers can be shown simultaneously.

You can see this behavior in action in our Multiple manual popovers example (source).

The beforetoggle and toggle events

You can respond to a popover being shown or hidden using the beforetoggle and toggle events:

• beforetoggle is fired just before a popover is shown or hidden. This can be used for example to prevent the popover being shown or hidden (using Event.preventDefault()), to add animation classes to a popover to animate it, or to cleanup the state of a popover after it has been used.
• toggle is fired just after a popover is shown or hidden. This is generally used to run other code in response to a popover toggle state changing.

Both of these events have a ToggleEvent event object. This event has the following features in addition to those inherited from the default Event object:

• The oldState and newState properties indicate which state the popover has just transitioned from and to, allowing you to respond specifically to a popover opening or closing.
• The source property contains a reference to the HTML popover control element that initiated the toggle, allowing you to run different code in response to the toggle event depending on which control initiated it.

Typical usage might look something like this:

const popover = document.getElementById("mypopover");

popover.addEventListener("toggle", (e) => {
  console.log(e.newState);
});

See the previous reference links for more information and examples.

Showing popovers via JavaScript

You can also control popovers using a JavaScript API.

The HTMLElement.popover property can be used to get or set the popover attribute. This can be used to create a popover via JavaScript, and is also useful for feature detection. For example:

function supportsPopover() {
  return Object.hasOwn(HTMLElement.prototype, "popover");
}

Similarly:

• HTMLButtonElement.popoverTargetElement and HTMLInputElement.popoverTargetElement provide an equivalent to the popovertarget attribute, allowing you to set up the control button(s) for a popover, although the property value taken is a reference to the popover DOM element to control.
• HTMLButtonElement.popoverTargetAction and HTMLInputElement.popoverTargetAction provide an equivalent to the popovertargetaction global HTML attribute, allowing you to specify the action taken by a control button.

Putting these three together, you can programmatically set up a popover and its control button, like so:

const popover = document.getElementById("mypopover");
const toggleBtn = document.getElementById("toggleBtn");

const keyboardHelpPara = document.getElementById("keyboard-help-para");

const popoverSupported = supportsPopover();

if (popoverSupported) {
  popover.popover = "auto";
  toggleBtn.popoverTargetElement = popover;
  toggleBtn.popoverTargetAction = "toggle";
} else {
  toggleBtn.style.display = "none";
}

You also have several methods to control showing and hiding:

• HTMLElement.showPopover() to show a popover.
• HTMLElement.hidePopover() to hide a popover.
• HTMLElement.togglePopover() to toggle a popover.

For example, you might want to provide the ability to toggle a help popover on and off by clicking a button or pressing a particular key on the keyboard. The first one could be achieved declaratively, or you could do it using JavaScript as shown above.

For the second one, you could create an event handler that programs two separate keys — one to open the popover and one to close it again:

document.addEventListener("keydown", (event) => {
  if (event.key === "h") {
    if (popover.matches(":popover-open")) {
      popover.hidePopover();
    }
  }

  if (event.key === "s") {
    if (!popover.matches(":popover-open")) {
      popover.showPopover();
    }
  }
});

This example uses Element.matches() to programmatically check whether a popover is currently showing. The :popover-open pseudo-class matches only popovers that are currently being shown. This is important to avoid the errors that are thrown if you try to show an already-shown popover, or hide an already-hidden popover.

Alternatively, you could program a single key to show and hide the popover like this:

document.addEventListener("keydown", (event) => {
  if (event.key === "h") {
    popover.togglePopover();
  }
});

See our Toggle help UI example (source) to see the popover JavaScript properties, feature detection, and togglePopover() method in action.

Nested popovers

There is an exception to the rule about not displaying multiple auto popovers at once — when they are nested inside one another. In such cases, multiple popovers are allowed to both be open at the same time, due to their relationship with each other. This pattern is supported to enable use cases such as nested popover menus.

There are three different ways to create nested popovers:

1. Direct DOM descendants:

   html

   <div popover>
     Parent
     <div popover>Child</div>
   </div>
   

2. Via invoking/control elements:

   html

   <div popover>
     Parent
     <button popovertarget="foo">Click me</button>
   </div>
   
   <div popover id="foo">Child</div>
   

3. Via the anchor attribute:

   html

   <div popover id="foo">Parent</div>
   
   <div popover anchor="foo">Child</div>
   

See our Nested popover menu example (source) for an example. You'll notice that quite a few event handlers have been used to display and hide the subpopover appropriately during mouse and keyboard access, and also to hide both menus when an option is selected from either. Depending on how you handle loading of new content, either in an SPA or multi-page website, some of all of these may not be necessary, but they have been included in this demo for illustrative purposes.

Using "hint" popover state

There is a third type of popover you can create — hint popovers, designated by setting popover="hint" on your popover element. hint popovers do not close auto popovers when they are displayed, but will close other hint popovers. They can be light dismissed and will respond to close requests.

This is useful for situations where, for example, you have toolbar buttons that can be pressed to show UI popovers, but you also want to reveal tooltips when the buttons are hovered, without closing the UI popovers.

hint popovers tend to be shown and hidden in response to non-click JavaScript events such as mouseover/mouseout and focus/blur. Clicking a button to open a hint popover would cause an open auto popover to light-dismiss.

See our popover hint demo (source) for an example that behaves exactly as described above. The demo features a button bar; when pressed, the buttons show auto popup sub-menus inside which further options can be selected. However, when hovered over or focused, the buttons also show tooltips (hint popovers) to give the user an idea of what each button does, which do not hide a currently-showing sub-menu.

In the below sections, we'll walk through all the important parts of the code.

Creating the sub-menus with popover="auto"

The popup sub-menus are created declaratively, using auto popovers.

First, the control buttons:

<section id="button-bar">
  <button popovertarget="submenu-1" popovertargetaction="toggle" id="menu-1">
    Menu A
  </button>

  <button popovertarget="submenu-2" popovertargetaction="toggle" id="menu-2">
    Menu B
  </button>

  <button popovertarget="submenu-3" popovertargetaction="toggle" id="menu-3">
    Menu C
  </button>
</section>

Now, the popovers themselves:

<div id="submenu-1" popover="auto">
  <button>Option A</button><br /><button>Option B</button>
</div>
<div id="submenu-2" popover="auto">
  <button>Option A</button><br /><button>Option B</button>
</div>
<div id="submenu-3" popover="auto">
  <button>Option A</button><br /><button>Option B</button>
</div>

Creating the tooltips with popover="hint"

The sub-menu popovers work fine as they are, opening when the toolbar buttons are pressed, but how do we also show tooltips on button hover/focus? First, we create the tooltips in HTML, using hint popovers:

<div id="tooltip-1" class="tooltip" popover="hint">Tooltip A</div>
<div id="tooltip-2" class="tooltip" popover="hint">Tooltip B</div>
<div id="tooltip-3" class="tooltip" popover="hint">Tooltip C</div>

To control the showing/hiding, we need to use JavaScript. First of all, we grab references to the hint popovers and the control buttons in two separate NodeLists using Document.querySelectorAll():

const tooltips = document.querySelectorAll(".tooltip");
const btns = document.querySelectorAll("#button-bar button");

Next, we create a function, addEventListeners(), which sets four event listeners (via EventTarget.addEventListener()) on a given <button>, chosen by grabbing the <button> at a specific index value of the btns NodeList. The functions act on the hint popover at the same index value of the tooltips NodeList, allowing us to keep the buttons and the tooltips in sync — showing/hiding the correct tooltip when a button is interacted with.

The event listeners show the popover on mouseover and focus, and hide the popover on mouseout and blur, meaning that the tooltips can be accessed via mouse and keyboard.

function addEventListeners(i) {
  btns[i].addEventListener("mouseover", () => {
    tooltips[i].showPopover({ source: btns[i] });
  });

  btns[i].addEventListener("mouseout", () => {
    tooltips[i].hidePopover();
  });

  btns[i].addEventListener("focus", () => {
    tooltips[i].showPopover({ source: btns[i] });
  });

  btns[i].addEventListener("blur", () => {
    tooltips[i].hidePopover();
  });
}

Finally, we use a for loop to iterate through the <buttons> in the btns NodeList, calling the addEventListeners() function for each one so that all of them have the desired event listeners set.

for (let i = 0; i < btns.length; i++) {
  addEventListeners(i);
}

Styling popovers

This section covers some CSS selection and positioning techniques relevant to popovers.

Selecting popovers

You can select all popovers with a simple attribute selector:

[popover] {
  /* Declarations here */
}

Alternatively, you can select a specific popover type by including a value in the attribute selector:

[popover="auto"] {
  /* Declarations here */
}

You can select only popovers that are showing using the :popover-open pseudo-class:

:popover-open {
  /* Declarations here */
}

Styling the popover backdrop

The ::backdrop pseudo-element is a full-screen element placed directly behind showing popover elements in the top layer, allowing effects to be added to the page content behind the popover(s) if desired. You might for example want to blur out the content behind the popover to help focus the user's attention on it:

::backdrop {
  backdrop-filter: blur(3px);
}

See our Popover blur background example (source) for an idea of how this renders.

Positioning popovers

When looking at the first couple of examples linked at the start of the article, you may have noticed that the popovers appear in the middle of the viewport, wrap their content, and have a black border. This is the default styling, achieved using the following rule in the UA stylesheet:

[popover] {
  position: fixed;
  inset: 0;
  width: fit-content;
  height: fit-content;
  margin: auto;
  border: solid;
  padding: 0.25em;
  overflow: auto;
  color: CanvasText;
  background-color: Canvas;
}

To apply custom sizing and position the popover somewhere else, you could override the above styles with something like this:

:popover-open {
  width: 200px;
  height: 100px;
  position: absolute;
  inset: unset;
  bottom: 5px;
  right: 5px;
  margin: 0;
}

You can see an isolated example of this in our Popover positioning example (source).

Popover anchor positioning

There is another useful positioning option that the Popover API provides. If you want to position a popover relative to its invoker rather than the viewport or a positioned ancestor, you can take advantage of the fact that popovers and their invokers have an implicit anchor reference.

Associating any kind of popover with its invoker creates an implicit anchor reference between the two. This causes the invoker to become the popover's anchor element, meaning that you can position the popover relative to it using CSS anchor positioning.

Because the association between the popover and the invoker is implicit, an explicit association does not need to be made using the anchor-name and position-anchor properties. However, you still need to specify the positioning CSS.

For example, you could use a combination of anchor() function values set on inset properties, and anchor-center values set on alignment properties:

.my-popover {
  margin: 0;
  inset: auto;
  bottom: calc(anchor(top) + 20px);
  justify-self: anchor-center;
}

Or you could use a position-area property:

.my-popover {
  margin: 0;
  inset: auto;
  position-area: top;
}

When using