Flyout
A non-modal overlay, showing contextually relevant content.
Flyout overlays with pointers
Flyout is a composite pattern containing an element that hosts a non-modal overlay. The overlay typically discloses secondary or tertiary content related to the host element.
Flyout forms the basis of the following composite patterns:
The pattern discussed here is the more generic use-case, where the flyout overlay may contain some other kind of content than listed above.
- flyout: the composite pattern as a *whole*, containing an overlay and it's host
- host: the element that hosts the overlay
- overlay: the non-modal overlay that contains the content related to it's host
- content: the actual content of the overlay
- expanded/collapsed: the overlay state (visible or hidden)
The overlay can hold any kind of content, but for an overlay that demands user acknowledgement or input, or with additional rich interactions, consider using a dialog instead.
The overlay expands or collapses via any combination of the following events:
- Click event of host
- Hover event of host
- Focus event of host
- System event at page load or after some arbitrary time
A link must not be the host of a click-activated flyout. Clicking the host should always navigate to the URL in this case.
Overlay must be non-modal (i.e. must not trap keyboard focus or mask page background). For modal behaviour please consider the dialog pattern instead.
Overlay must be placed directly after the host in DOM. This ensures natural tab order and reading order without JavaScript.
If system-activated, overlay must remain onscreen until explicitly dismissed by the user,
If focus-activated, overlay should not contain long blocks of interactive elements. This measure prevents keyboard users from having to tab through secondary or tertiary content inside of the overlay.
This section provides interaction guidelines for keyboard, screen reader, and pointing devices.
Tab order must flow directly from host into first focusable element inside overlay. If the overlay has no focusable element, tab order flows to next page control instead.
If not system-activated, host must be keyboard focus-able.
If focus-activated, flyout must expand when host receives keyboard focus.
If focus-activated, flyout must collapse when flyout loses keyboard focus.
If click-activated, flyout must expand overlay when host receives keyboard click.
Reading order must flow directly from host into overlay.
If system-activated and high-priority, screen reader must announce presence and/or content overlay.
If hover-activated, flyout must expand when host receives mouse hover.
If click-activated, flyout must expand when host receives mouse click.
If system-activated, flyout must collapse when clicking close button.
Hover behaviour can be problematic or impossible for touch. You may wish to consider using the Infotip pattern instead.
If click-activated, flyout must expand when host receives tap.
if system-activated, flyout must close when tapping close button.
Let's examine a click-activated flyout. Click-activated flyouts typically occur with buttons, where clicking the button expands the flyout.
The key things to consider are:
- 1.Server-side rendering or client-side rendering of overlay content (or both)
- 2.Placement of overlay element in relation to host
- 3.Using aria-expanded state to toggle CSS display
- 4.Determining the live-region property
Content rendered by the server will be visible by default before & without CSS or JavaScript. If the content is secondary in nature, you may wish to render the content on the client instead.
Whatever progressive enhancement strategy you choose, the following structure is the goal:
<span class="flyout flyout--click">
<button class="flyout__host" type="button" disabled>Toggle Flyout</button>
<span aria-live="off">
<div class="flyout__overlay">
<!-- flyout content -->
</div>
</span>
</span>
Notice placement of the host (the button) directly before the overlay element. This allows natural keyboard and reading order from the host into the overlay.
An optional live-region element wraps the overlay. The live-region property may be set to "off", "polite" or "assertive".
The overlay can be absolute or fixed positioned:
.flyout__overlay {
display: none;
position: absolute;
z-index: 1;
}
We have hidden the overlay by default (display: none). We use the aria-expanded state of the host to control the display of the overlay:
.flyout__host[aria-expanded=true] ~ [aria-live] .flyout__overlay {
display: block;
}
CSS alone cannot trigger the expanded state, so we require a small amount of Javascript to handle this behaviour:
document.querySelector('.flyout__host').addEventListener('click', function() {
const isExpanded = this.getAttribute('aria-expanded') === 'true';
this.setAttribute('aria-expanded', isExpanded ? 'false' : 'true');
});
Clicking the button with mouse, keyboard or touch will now toggle the aria-expanded state of the button.
This boolean attribute signifies the expanded state of the host element.
If wishing to announce the content of the flyout when it expands, set aria live to polite or assertive.
Last modified 8mo ago