Firefox 158 release notes for developers (Beta)

Changes for web developers

Accessibility

• The aria-busy attribute is now supported in Firefox for Android (desktop support has been available for a long time). This ARIA state indicates whether an element is currently being modified. It allows assistive technologies to wait until changes to the content are complete before informing users of the update. For example, a screen reader can wait until a live region has finished updating before announcing the changes. (Firefox bug 908042).

CSS

• CSS typed arithmetic is now supported, which enables using functions such as calc() to divide two values of the same data type, even if they use different units. The resulting unitless quotients can then be converted to other data types, creating useful relationships between different values on a page. (Firefox bug 2067411).

HTTP

• The default HTTP Accept header for image requests now includes image/jxl, following support for the JPEG XL image format. The new value is image/avif,image/jxl,image/webp,image/png,image/svg+xml,image/*;q=0.8,*/*;q=0.5 (see List of default Accept values). (Firefox bug 2065096).

APIs

• The WebTransport.getStats() method is now supported. This method returns statistics for the transport's underlying connection and its datagrams. (Firefox bug 2007202).
• The navigate option of the Notification() constructor and the ServiceWorkerRegistration.showNotification() method is now supported. This option specifies a URL to navigate to after the user clicks the generated system notification. Once a notification is created, you can retrieve the URL from the Notification.navigate property. (Firefox bug 2069920).
• The WebGPU float32-blendable feature is now supported (see GPUSupportedFeatures). This allows blending of GPUTextures that use the r32float, rg32float, or rgba32float format. (Firefox bug 1931630).
• The PerformanceResourceTiming.deliveryType property is now supported, which indicates how a resource was delivered; for example, whether it came from the cache. (Firefox bug 1914120).

DOM

• The SVGGraphicsElement.getBBox() method now honors the fill and stroke properties of its options argument when called on <tspan> and <textPath> elements. This allows you to get a bounding box that includes the stroke of a text span, as you already could for a whole <text> element. (Firefox bug 2072680).

WebDriver conformance (WebDriver BiDi, Marionette)

General

• Added support for setting the camera and microphone permissions with the permissions.setPermission command in WebDriver BiDi and the WebDriver:SetPermission command in Marionette. This allows tests to grant or deny access to media devices without prompting the user. (Firefox bug 2070577).
• Changed the touch start and touch move tolerances to zero in automation, so that touch actions now scroll from exactly the position at which they are dispatched, without small initial movements being absorbed. (Firefox bug 2055661).

WebDriver BiDi

• Added support for the imageSize argument to the browsingContext.captureScreenshot command, which allows clients to specify the maximum size of the resulting screenshot image. (Firefox bug 2069002).
• Added support for the destinationFolder argument to the browsingContext.startScreencast command, which allows clients to choose the folder where the recorded video file is saved. (Firefox bug 2072616).

Marionette

• Fixed the WebDriver:TakeScreenshot command to return an unable to capture screen error when the width or height of the captured image is zero. (Firefox bug 1492357).

Other

• Support for the JPEG XL image format (image/jxl) is now enabled by default. JPEG XL is a royalty-free raster image format that supports lossy and lossless compression, transparency, animation, and HDR. It can also losslessly transcode existing JPEG images. (Firefox bug 2065096).

Changes for add-on developers

• publicSuffix.isKnownSuffix() now throws an error when passed an invalid hostname, instead of returning false. (Firefox bug 2066620)
• Adds runtime.getVersion() to return the extension's version as declared in the manifest. (Firefox bug 1992418)

Experimental web features

These features are shipping in Firefox 158 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.

• corner-shape properties: layout.css.corner-shape.enabled

  The corner-shape shorthand property and its constituent longhand properties are now supported in Nightly. These properties let you customize corner shapes using one of the <corner-shape-value> keyword values or the superellipse() function. (Firefox bug 2070927).

• On-device speech recognition: media.webspeech.recognition.enable

  On-device speech recognition is now supported in Nightly, on desktop only. This allows you to perform speech recognition via the Web Speech API directly in the browser, rather than relying on a cloud service. (Firefox bug 2069803).

• Streaming request bodies: dom.fetch.streaming_upload

  Enabled in Nightly only, you can now set a ReadableStream as a request body (for example, via the Request() constructor or the Window.fetch() method). This allows you to stream uploads incrementally rather than having to wait for the whole body to be available. (Firefox bug 1594633).