Firefox 126 for developers

Removals

Removals

Removals

Removals

• The zstd directive of the Content-Encoding HTTP header is now supported, allowing decoding of server-sent content encoded with the Zstandard compression algorithm (Firefox bug 1871963).

Removals

Removals

• IDBFactory.databases() is now supported for enumerating available IndexedDB API databases (Firefox bug 934640).
• The URL.parse() static method is now supported for creating URL objects. This returns null if the passed parameters do not define a valid URL, and can hence be used as a non-throwing alternative to creating URL object with the URL constructor (Firefox bug 1823354).
• The Screen Wake Lock API is now supported, allowing a web application to request that the screen not be dimmed or locked while it is active. This is useful for navigation and reading applications, and other applications where the screen doesn't get regular tactile input when in use, which would otherwise keep the screen awake. The API is accessed through Navigator.wakeLock in secure contexts, which returns a WakeLock. This can be used to request a WakeLockSentinel that can be used to monitor the status of the wake lock, and release it manually. (Firefox bug 1589554, Firefox bug 1874849).
• All RTCIceCandidate properties and methods are now supported and match the specification, with the exception of unimplemented properties: relayProtocol and url.
  • The following properties were made read-only: candidate, sdpMid, sdpMLineIndex, usernameFragment,
  • The following properties were added: foundation, component, priority, address, protocol, port, type, tcpType, relatedAddress, relatedPort, usernameFragment.
  (Firefox bug 1322186).

DOM

• The ability to define states for custom elements and match them using CSS selectors is now available by default. The custom states are represented as custom identifiers that can be added to or removed from the element's ElementInternals.states property (a CustomStateSet). The CSS :state() pseudo-class takes a custom identifier as an argument and matches custom elements if the identifier is present in their set of states. (Firefox bug 1887543).

Media, WebRTC, and Web Audio

Removals

• The marquee events bounce, finish, and start have been removed from HTMLMarqueeElement, along with the corresponding event handler attributes defined on the <marquee> HTML element (Firefox bug 1689705).

Removals

General

WebDriver BiDi

Marionette

• The commands.onCommand event now passes the tab argument to the event listener. This enables extensions to apply a triggered shortcut to the page in which it was issued, without the need to call the tabs.query() method (Firefox bug 1843866).
• The runtime.MessageSender type now includes the origin property. This enables message or connection requests to see the page or frame that opened the connection. This is useful for identifying if the origin can be trusted if it isn't apparent from the URL (Firefox bug 1787379).
• The "webRequestAuthProvider" permission is now supported. This provides compatibility with Chrome for requesting permission for webRequest.onAuthRequired in Manifest V3 (Firefox bug 1820569).
• The options_page manifest key is provided as an alias of the options_ui key. This has been provided to offer extensions better compatibility with Chrome (Firefox bug 1816960).

These features are newly shipped in Firefox 126 but are disabled by default. To experiment with them, search for the appropriate preference on the about:config page and set it to true. You can find more such features on the Experimental features page.