Experimental features in Firefox

Layout for input type="search" has been updated. This causes a search field to have a clear icon once someone starts typing in it, to match other browser implementations. (See Firefox bug 558594 for more details.)

The HTMLSelectElement.showPicker() method programmatically launches the browser picker for a <select> element, triggered by user interaction. (See Firefox bug 1854112 for more details.)

HTML password input elements (<input type="password">) include an "eye" icon that can be toggled to display or obscure the password text (Firefox bug 502258).

This feature renders control characters (Unicode category Cc) other than tab (U+0009), line feed (U+000A), form feed (U+000C), and carriage return (U+000D) as a hexbox when they are not expected. (See Firefox bug 1099557 for more details.)

The initial-letter CSS property is part of the CSS Inline Layout specification and allows you to specify how dropped, raised, and sunken initial letters are displayed. (See Firefox bug 1223880 for more details.)

The content-visibility CSS property value auto allows content to skip rendering if it is not relevant to the user. (See Firefox bug 1798485 for more details.)

Note that the related contentvisibilityautostatechange event and associated ContentVisibilityAutoStateChangeEvent interface were added in version 110, and are gated by the same preference. These can be used by application code to monitor visibility changes and stop processes related to rendering the element when the user agent is skipping its contents. (See Firefox bug 1791759 for more details.)

Support for using a single <number> as a <ratio> when specifying the aspect ratio for a media query. (See Firefox bug 1565562 for more details.)

The backdrop-filter property applies filter effects to the area behind an element. (See Firefox bug 1178765 for more details.)

The CSS ray() function is a way to define an offset-path. The function defines the path as a line segment that begins from an offset-position and extends in the direction of the specified angle (Firefox bug 1582554).

In version 112, the <ray_size> optional parameter was added to the function. If no <ray_size> parameter is provided, it assumes the default value of closest-side (Firefox bug 1820071).

In version 116, the at <position> optional parameter was added to the function. If omitted, the offset-position value of the element is used. If both at <position> and offset-position values are absent, offset-position: auto is used as ray's starting position, which places the element at the top left corner of the element's box. (Firefox bug 1820070).

Adds support for a masonry-style layout based on grid layout where one axis has a masonry layout and the other has a normal grid layout. This allows developers to easily create gallery style layouts like on Pinterest. See Firefox bug 1607954 for more details.

The fit-content() function as it applies to width and other sizing properties. This function is already well-supported for CSS Grid Layout track sizing. (See Firefox bug 1312588 for more details.)

Earlier called "scroll-linked animations", a scroll-driven animation depends on the scroll position of a scrollbar instead of time or some other dimension. The scroll-timeline-name and scroll-timeline-axis properties (and the scroll-timeline shorthand property) allow you to specify that a particular scrollbar in a particular named container can be used as the source for a scroll-driven animation. The scroll timeline can then be associated with an animation by setting the animation-timeline property to the name value defined using scroll-timeline-name.

When using the scroll-timeline shorthand property, the order of the property values must be scroll-timeline-name followed by scroll-timeline-axis. The longhand and shorthand properties are both available behind the preference.

You can alternatively use the scroll() functional notation with animation-timeline to indicate that a scrollbar axis in an ancestor element will be used for the timeline.

For more information, see Firefox bug 1807685, Firefox bug 1804573, Firefox bug 1809005, Firefox bug 1676791, Firefox bug 1754897, and Firefox bug 1737918.

The @font-face src descriptor now supports the tech() function, allowing fallback of whether a font resource is downloaded based on whether the user-agent supports a particular font feature or technology. See Firefox bug 1715546 for more details.

The CSS font-variant-emoji property allows you to set a default presentation style for displaying emojis. See (Firefox bug 1461589) for more details.

The page-orientation CSS descriptor for the @page at-rule controls the rotation of a printed page. It handles the flow of content across pages when the orientation of a page is changed. This behavior differs from the size descriptor in that a user can define the direction in which to rotate the page. See (Firefox bug 1673987) for more details.

The CSS prefers-reduced-transparency media feature lets you detect if a user has enabled the setting to minimize the amount of transparent or translucent layer effects on their device. See (Firefox bug 1736914) for more details.

The CSS inverted-colors media feature lets you detect if a user agent or the underlying operating system is inverting colors. See (Firefox bug 1794628) for more details.

The CSS view-timeline-name property lets you give a name to particular element, identifying that its ancestor scroller element is the source of a view progress timeline. The name can then be assigned to the animation-timeline, which then animates the associated element as it moves through the visible area of its ancestor scroller. See (Firefox bug 1737920) for more details.

The CSS view() function lets you specify that the animation-timeline for an element is a view progress timeline, which will animate the element as it moves through the visible area of its ancestor scroller. The function defines the axis of the parent element that supplies the timeline, along with the inset within the visible area at which the animation starts and begins. See (Firefox bug 1808410) for more details.

The CSS offset-position property defines the initial position of an element on a path. A new keyword called normal has been added to the syntax of the property. When using this keyword, the initial starting position of an element on an offset-path depends on the CSS function used – path() or ray() – to specify the value of the offset-path property. For more information, see offset-position. See (Firefox bug 1559232) for more details.

The CSS rect() and xywh() shape functions enable you to define a rectangle using the <basic-shape> data type. In CSS properties such as offset-path, these functions are used to define the shape of the path along which an element moves. Using the rect() function, you specify the rectangle edge offsets from the top edge and left edges of the containing block. Using the xywh() function, you specify the rectangle edge offsets from the left and top edges of the containing block as well as the width and height of the rectangle. In both the functions, you can optionally round off the corners. For more details, see Firefox bug 1786161 for the rect() function and Firefox bug 1786160 for the xywh() function.

The CSS offset-path property now supports using url() to specify the ID of an SVG shape element. The referenced shape defines the shape of the path that an element will follow (Firefox bug 1598158).

The non-standard CSS zoom property is enabled in the Nightly release and lets you magnify an element similar to the transform property, but it affects the layout size of the element. See (Firefox bug 1855763 and Firefox bug 390936) for more details.

To ensure compatibility with these changes, the Vendor-prefixed transform properties and the Vendor-prefixed transition properties are disabled in the Nightly release. These changes are described in the following sections.

Vendor-prefixed transform properties

The -moz- prefixed CSS transform properties have been disabled in the Nightly release via the layout.css.prefixes.transforms preference being set to false (Firefox bug 1855763). Specifically, the disabled properties are:

• -moz-backface-visibility
• -moz-perspective
• -moz-perspective-origin
• -moz-transform
• -moz-transform-origin
• -moz-transform-style

Vendor-prefixed transition properties

The -moz- prefixed CSS transitions properties have been disabled in the Nightly release via the layout.css.prefixes.transitions preference being set to false (Firefox bug 1855763). Specifically, the disabled properties are:

• -moz-transition
• -moz-transition-delay
• -moz-transition-duration
• -moz-transition-property
• -moz-transition-timing-function

The SVGPathSeg APIs are being unshipped, and have been placed behind a preference. This includes: SVGPathSegList, SVGPathElement.getPathSegAtLength(), SVGAnimatedPathData. (See Firefox bug 1388931 for more details.)

The ArrayBuffer.prototype.transfer() and ArrayBuffer.prototype.transferToFixedLength() methods are used to transfer ownership of memory from one ArrayBuffer to another. The transferToFixedLength() method always creates a fixed length buffer, while transfer() may create a variable buffer, but only if the original buffer had a variable length. After transfer, the original buffer is detached from the original memory and hence unusable; the state can be checked using ArrayBuffer.prototype.detached. (See Firefox bug 1841113 for more details.)

Hit regions

Whether the mouse coordinates are within a particular area on the canvas is a common problem to solve. The hit region API allows you to define an area of your canvas and provides another possibility to expose interactive content on a canvas to accessibility tools.

WebGL: Draft extensions

When this preference is enabled, any WebGL extensions currently in "draft" status which are being tested are enabled for use. Currently, there are no WebGL extensions being tested by Firefox.

WebGPU API

The WebGPU API provides low-level support for performing computation and graphics rendering using the Graphics Processing Unit (GPU) of the user's device or computer. See Firefox bug 1602129 for our progress on this API.

The following experimental features include those found in the WebRTC API, the Web Audio API, the Media Source Extensions API, the Encrypted Media Extensions API, and the Media Capture and Streams API.

Asynchronous SourceBuffer add and remove

This adds the promise-based methods appendBufferAsync() and removeAsync() for adding and removing media source buffers to the SourceBuffer interface. See Firefox bug 1280613 and Firefox bug 778617 for more information.

AVIF compliance strictness

The image.avif.compliance_strictness preference can be used to control the strictness applied when processing AVIF images. This allows Firefox users to display images that render on some other browsers, even if they are not strictly compliant.

Permitted values are:

• 0: Accept images with specification violations in both recommendations ("should" language) and requirements ("shall" language), provided they can be safely or unambiguously interpreted.
• 1 (default): Reject violations of requirements, but allow violations of recommendations.
• 2: Strict. Reject any violations in requirements or recommendations.

JPEG XL support

Firefox supports JPEG XL images if this feature is enabled. See Firefox bug 1539075 for more details.

Note that, as shown below, the feature is only available on Nightly builds (irrespective of whether the preference is set).

OpenFont COLRv1 fonts

This feature provides support for the OpenFont COLRv1 font specification. This enables compression-friendly color vector fonts with gradients, compositing and blending to be loaded using the CSS @font-face rule, or the CSS Font Loading API. See Firefox bug 1740530 for more details.

CSS Properties and Values API

The CSS Properties and Values API allows developers to register custom CSS properties through JavaScript via registerProperty() or in CSS using the @property at-rule. Registering properties using these two methods allows for type checking, default values, and properties that do or do not inherit values from their parent elements. See Firefox bug 1840480 for more details.

CSS Custom Highlight API

The CSS Custom Highlight API provides a mechanism for styling arbitrary text ranges in a document (generalizing the behavior of other highlight pseudo-elements such as ::selection, ::spelling-error, ::grammar-error, and ::target-text). The ranges are defined in JavaScript using Range instances grouped in a Highlight, and then registered with a name using HighlightRegistry. The CSS ::highlight pseudo-element is used to apply styles to a registered highlight. See Firefox bug 1703961 for more details.

Preloading of service worker resources on navigation

The NavigationPreloadManager interface can be used to enable preloading of resources when navigating to a page. Preloading occurs in parallel with worker bootup, reducing the total time from start of navigation until resources are fetched.

WebVR API (Disabled)

The deprecated WebVR API is on the path for removal. It is disabled by default on all builds Firefox bug 1750902.

Popover API

Firefox now supports the Popover API.

The following Web APIs are now implemented:

• HTMLButtonElement.popoverTargetElement and HTMLButtonElement.popoverTargetAction.
• HTMLInputElement.popoverTargetElement and HTMLInputElement.popoverTargetAction.
• HTMLElement.popover, HTMLElement.hidePopover(), HTMLElement.showPopover(), and HTMLElement.togglePopover().
• HTMLElement beforetoggle event, HTMLElement toggle_event event, and ToggleEvent.

CSS updates include:

• :popover-open
• ::backdrop has been extended to support popovers

The following HTML global attributes are supported:

• popovertarget
• popovertargetaction

See Firefox bug 1823757 for more details.

HTMLMediaElement method: setSinkId()

HTMLMediaElement.setSinkId() allows you to set the sink ID of an audio output device on an HTMLMediaElement, thereby changing where the audio is being output. See Firefox bug 934425 for more details.

HTMLMediaElement properties: audioTracks and videoTracks

Enabling this feature adds the HTMLMediaElement.audioTracks and HTMLMediaElement.videoTracks properties to all HTML media elements. However, because Firefox doesn't currently support multiple audio and video tracks, the most common use cases for these properties don't work, so they're both disabled by default. See Firefox bug 1057233 for more details.

ClipboardItem

The ClipboardItem interface of the Clipboard API is now supported and Clipboard.write() accepts a sequence of clipboard items instead of the previously implemented dataTransfer object. It is available behind the pref dom.events.asyncClipboard.clipboardItem which was previously dom.events.asyncClipboard.dataTransfer. See Firefox bug 1619947 for more details.

ClipboardRead

The Clipboard.read() method of the Clipboard interface is also now available under the dom.events.asyncClipboard.read preference, when previously it was under dom.events.asyncClipboard.clipboardItem. (See Firefox bug 1701512 for more details.)

HTML Sanitizer API

The HTML Sanitizer API allow developers to take untrusted strings of HTML and sanitize them for safe insertion into a document's DOM. Default elements within each configuration property (those to be sanitized) are still under consideration. Due to this the config parameter has not been implemented (see the constructor for more information). See Firefox bug 1673309 for more details.

GeometryUtils methods: convertPointFromNode(), convertRectFromNode(), and convertQuadFromNode()

The GeometryUtils methods convertPointFromNode(), convertRectFromNode(), and convertQuadFromNode() map the given point, rectangle, or quadruple from the Node on which they're called to another node. (See Firefox bug 918189 for more details.)

GeometryUtils method: getBoxQuads()

The GeometryUtils method getBoxQuads() returns the CSS boxes for a Node relative to any other node or viewport. (See Firefox bug 917755 for more details.)

Custom element state pseudo-class

Custom elements can expose their internal state via the states property as a CustomStateSet. A CSS custom state pseudo-class such as :--somestate can match that element's state. (See Firefox bug 1861466 for more details.)

Primary payment handling

The Payment Request API provides support for handling web-based payments within web content or apps. Due to a bug that came up during testing of the user interface, we have decided to postpone shipping this API while discussions over potential changes to the API are held. Work is ongoing. (See Firefox bug 1318984 for more details.)

The Web Share API allows sharing of files, URLs and other data from a site. This feature is enabled on Android in all builds, but behind a preference on Desktop (unless specified below).

ScreenOrientation.lock()

The ScreenOrientation.lock() method allows a device to be locked to a particular orientation, if supported by the device and allowed by browser pre-lock requirements. Typically locking the orientation is only allowed on mobile devices when the document is being displayed full screen. See Firefox bug 1697647 for more details.

The Prioritized Task Scheduling API provides a standardized way to prioritize all tasks belonging to an application, whether they defined in a website developer's code, or in third party libraries and frameworks.

This is enabled on Firefox Nightly (only) from Firefox 101. No preference is provided to allow it to be enabled in other releases.

Notifications have the requireInteraction property set to true by default on Windows systems and in the Nightly release (Firefox bug 1794475).

In order to help mitigate man-in-the-middle (MitM) attacks caused by Flash content on encrypted pages, a preference has been added to treat OBJECT_SUBREQUESTs as active content. See Firefox bug 1190623 for more details.

These two preferences add a "Not secure" text label in the address bar next to the traditional lock icon when a page is loaded insecurely (that is, using HTTP rather than HTTPS). See Firefox bug 1335970 for more details.

When enabled, this preference causes Firefox to automatically upgrade requests for media content from HTTP to HTTPS on secure pages. The intent is to prevent mixed-content conditions in which some content is loaded securely while other content is insecure. If the upgrade fails (because the media's host doesn't support HTTPS), the media is not loaded. (See Firefox bug 1435733 for more details.)

This also changes the console warning; if the upgrade succeeds, the message indicates that the request was upgraded, instead of showing a warning.

Permissions Policy allows web developers to selectively enable, disable, and modify the behavior of certain features and APIs in the browser. It is similar to CSP but controls features instead of security behavior. This is implemented in Firefox as Feature Policy, the name used in an earlier version of the specification.

Note that supported policies can be set through the allow attribute on <iframe> elements even if the user preference is not set.

The Clear-Site-Data HTTP response header cache directive clears the browser cache for the requesting website.

SameSite cookies have a default value of Lax. With this setting, cookies are only sent when a user is navigating to the origin site, not for cross-site subrequests to load images or frames into a third party site and so on. For more details see Firefox bug 1617609.

The 103 Early Hints HTTP information response status code may be sent by a server to allow a user agent to start preloading resources while the server is still preparing the full response. Note that using the header to preconnect to sites is already supported. For more details see Firefox bug 1813035.

The Access-Control-Allow-Headers is a response header to a CORS preflight request, that indicates which request headers may be included in the final request. The response directive can contain a wildcard (*), which indicates that the final request may include all headers except the Authorization header.

By default, Firefox includes the Authorization header in the final request after receiving a response with Access-Control-Allow-Headers: *. Set the preference to false to ensure Firefox does not include the Authorization header. For more details see Firefox bug 1687364.

Mozilla's developer tools are constantly evolving. We experiment with new ideas, add new features, and test them on the Nightly and Developer Edition channels before letting them go through to beta and release. The features below are the current crop of experimental developer tool features.

This feature displays a button on the console's command line that lets you change the context in which the expression you enter will be executed. (See Firefox bug 1605154 and Firefox bug 1605153 for more details.)

Mouse gestures are used to simulate mobile gestures like swiping/scrolling, double-tap and pinch-zooming and long-press to select/open the context menu. (See Firefox bug 1621781, Firefox bug 1245183, and Firefox bug 1401304 for more details.)

[1] Support for zooming using the double-tap gesture was added in Firefox 76. The other gestures were added for Firefox 79.

The Network Monitor displays information for server-sent events. (See Firefox bug 1405706 for more details.)

The CSS Rules View can display browser compatibility tooltips next to any CSS properties that have known issues. For more information see: Examine and edit HTML > Browser Compat Warnings.

This feature lets you enable smooth pinch zooming on desktop computers without requiring layout reflows, just like mobile devices do. (See Firefox bug 1245183 and Firefox bug 1620055 for more details.)

• Firefox developer release notes
• Firefox Nightly
• Firefox Developer Edition