This article provides information about the changes in Firefox 132 that affect developers. Firefox 132 was released onOctober 29, 2024.

Changes for web developers

HTML

No notable changes

CSS

• Thetext-emphasis-position property now supports theauto value to bring it inline withtext-underline-position (Firefox bug 1919658).
• CSS now supports theNested declaration rule, which means that nested CSS is now parsed in the correct order (Firefox bug 1918408).

Removals

• The-moz-user-modify CSS property has been removed. This property has been deprecated in favor of thecontenteditable global attribute. (Firefox bug 1920118).

JavaScript

• The(?ims-ims:...) regular expression modifiers allow you to make changes to only take effect in a specific part of a regex pattern. (Firefox bug 1913752 &Firefox bug 1899813).

HTTP

• Thedefault/document value of the HTTPAccept header was changed totext/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8.This removes image MIME types that sometimes caused compatibility issues, and aligns with the fetch specification and Safari. (Firefox bug 1917177).

Removals

• HTTP/2 Server Push is deactivated by default with the preferencenetwork.http.http2.allow-push now set tofalse.This feature is no longer supported by any other major browser, and the implementation may be completely removed in a future release. (Firefox bug 1915848).

Privacy

• Allthird-party cookies are now blocked inStrict Enhanced Tracking Protection. (Firefox bug 1918037).

APIs

• ThedrawingBufferColorSpace andunpackColorSpace properties of theWebGLRenderingContext andWebGL2RenderingContext interfaces are now supported. These specify the color space of the WebGL drawing buffer, and the color space to convert to when importing textures, respectively. (Firefox bug 1885491,Firefox bug 1885446).
• TheNotification.silent property is now supported, which controls whether system notifications should be silent. Whensilent: true is specified in theNotification() constructor, the resulting system notification is issued without accompanying sounds or vibrations, regardless of device settings (Firefox bug 1809028).
• Thefetchpriority attribute of the<link>,<script>, and<img> elements, thefetchPriority property of theHTMLLinkElement,HTMLScriptElement, andHTMLImageElement interfaces, theoptions.priority parameter passed to theRequest() constructor, and thefetchpriority directive in the HTTPLink header, are now supported. These allow developers to provide a hint about the relative priority for fetching a particular resource compared to other resources of the same type, and can be used alongside other ways of setting the priority, such as preloading. (Firefox bug 1854077).
• TheCSSNestedDeclarations interface and associatedCSSNestedDeclarations.style property are now supported (Firefox bug 1918408).
• Themicrophone andcamerapermissions can now be used in thePermissions.query() method to test whether access to the corresponding hardware has been granted, denied, or still requires user approval. (Firefox bug 1609427 andFirefox bug 1915222).

Media, WebRTC, and Web Audio

• TherequestVideoFrameCallback() andcancelVideoFrameCallback() methods of theHTMLVideoElement interface are now supported. TherequestVideoFrameCallback() registers a callback function that runs when a new video frame is sent to the compositor. Developers can use this function to perform operations on each video frame, enabling more efficient painting to a canvas, video analysis, synchronization with external audio sources, and so on. The method returns a callback handle that can be passed tocancelVideoFrameCallback() in order to cancel the outstanding callback request. (Firefox bug 1919367,Firefox bug 1800882).
• TheMediaStreamTrack.getCapabilities() method is now supported. This returns an object detailing the accepted values or value range for each constrainable property of the associatedMediaStreamTrack (Firefox bug 1179084).

WebDriver conformance (WebDriver BiDi, Marionette)

WebDriver BiDi

• Implemented several improvements to make WebDriver BiDi commands more reliable when used during navigation or with newly created tabs. Previously commands such asbrowsingContext.setViewport were likely to fail due to anAbortError, they will now be retried a few times to avoid such issues. (Firefox bug 1854942,Firefox bug 1918287,Firefox bug 1918672,Firefox bug 1921756)
• ThebrowsingContext.contextCreated event is now correctly emitted for lazy-loaded frames. Previously the event would only be emitted when the iframe actually started loading its content. (Firefox bug 1878166)
• Network events are now correctly emitted for cached stylesheet requests. (Firefox bug 1879438)
• Network event timings were previously using the wrong unit and were provided in microseconds. They are now correctly set in milliseconds. (Firefox bug 1916685)
• TherequestTime from network event timings should now be more accurate and really match the time where the request actually started. (Firefox bug 1922390)

Experimental web features

These features are newly shipped in Firefox 132 but are disabled by default. To experiment with them, search for the appropriate preference on theabout:config page and set it totrue. You can find more such features on theExperimental features page.

• Cookie Store API:dom.cookieStore.enabled.

  TheCookie Store API is a modern,Promise-based method of managing cookies that does not block the event loop and does not rely onDocument (it can therefore be made available toservice workers). As of Firefox 132, a subset of the Cookie Store API has been implemented. (Firefox bug 1800882). This includes:

  • TheCookieStore interface, butpartitioned is not included in return values.
  • TheCookieChangeEvent interface, excludingpartitioned properties.
  • TheWindow.cookieStore property.
  • TheServiceWorkerGlobalScope.cookieStore property.

• Thefetch()keepalive option:dom.fetchKeepalive.enabled.

  The globalfetch() method has akeepalive initialization option. Whenkeepalive is set totrue, the browser will not abort the associated request if the page that initiated it is unloaded before the request is complete.

  This enables a fetch request to function as an alternative toNavigator.sendBeacon() when sending analytics at the end of a session, which has some advantages (you can use HTTP methods other thanPOST, customize request properties, and access the server response via the fetchPromise fulfillment). It is also available inservice workers. (Firefox bug 1906952).

• CloseWatcher:dom.closewatcher.enabled.TheCloseWatcher interface enables developers to implement components that can be closed using device-native mechanisms, in the same way as built-in components. For example, on Android you can close a dialog using the back button: this interface allows you to similarly close a custom sidebar. (Firefox bug 1888729).

• Promise.try():javascript.options.experimental.promise_try.Promise.try() is a convenience method that takes a callback of any kind (returns or throws, synchronously or asynchronously) and wraps its result in aPromise so that promise semantics (e.g.,.then(),.catch()) can be used to handle it (Firefox bug 1905364).

• JSON.parse with source:javascript.options.experimental.json_parse_with_source. TheJSON.parse source text access proposal extendsJSON.parse behavior to provide features to mitigate issues around loss of precision when converting values such as large floats and date values between JavaScript values and JSON text (Firefox bug 1913085,Firefox bug 1925334). Specifically, the following features are now available:

  • TheJSON.parse()reviver parametercontext argument: Provides access to the original JSON source text that was parsed.
  • JSON.isRawJSON(): Tests whether a value is an object returned byJSON.rawJSON().
  • JSON.rawJSON(): Creates a "raw JSON" object containing a piece of JSON text, which can then be included in an object to preserve the specified value when that object is stringified.