Firefox 110 release notes for developers

Changes for web developers

HTML

No notable changes.

CSS

• Container queries and container query length units are now supported by default. For more information on these queries and the related units of length, see the CSS Container Queries documentation (Firefox bug 1809720).
• The color-gamut media query is now supported (Firefox bug 1422237).
• The list attribute is supported in <input> elements with type="color" on Windows and Linux (Firefox bug 960984).
• The @page at-rule now supports named pages, which allows a user to create page breaks for specific selectors using the page property (Firefox bug 1787947)

JavaScript

• Serialization of native Error types now includes the stack property in workers when using Worker.postMessage() and structuredClone(). With this addition, cloning native error stacks now works for all methods that use the structured clone algorithm, in both the main thread and workers. (See Firefox bug 1774866 for more details.)

APIs

• The midi permission of the Permission API is now supported. This allows the permission status for using the Web MIDI API to be queried using navigator.permissions.query() (Firefox bug 1772166).

• ReadableStream now supports asynchronous iteration over the chunks in a stream using the for await...of syntax (Firefox bug 1734244).

• WebRTC now supports sending the set of available encodings when adding a transceiver to a peer connection, and also getting the active encoding associated with a sender. Specifically, RTCPeerConnection.addTransceiver() now supports using the sendEncodings option in the init parameter object, and active can be used to determine whether or not the encoding is being used to send data. (See Firefox bug 1676855 for more details.)

• WebRTC methods RTCRtpSender.getParameters(), RTCRtpSender.setParameters(), and RTCRtpReceiver.getParameters() are now compliant with the specification (Firefox bug 1401592).

DOM

• CSSContainerRule is supported, allowing JavaScript to access the name and query used in an @container at-rule definition (Firefox bug 1787173).

• Elements now lose focus if a style is applied that makes them ineligible to hold focus, such as hidden, and the blur event is fired. Focus then moves to the viewport. Previously focus would remain with the element. (See Firefox bug 1810077 for more details.)

WebDriver conformance (WebDriver BiDi, Marionette)

WebDriver BiDi

• Added support for the network.beforeRequestSent (Firefox bug 1790368), the network.responseStarted (Firefox bug 1790370), and the network.responseCompleted (Firefox bug 1790372) events.

• Added support for the browsingContext.captureScreenshot command to capture full page screenshots (Firefox bug 1800086).

• Added support for serialization and deserialization of generic platform objects (Firefox bug 1792524), and for NodeList and HTMLCollection platform objects (Firefox bug 1802284).

• Added a timestamp field to the browsingContext.domContentLoaded and browsingContext.load events (Firefox bug 1790378).

• Added a type field to the response for script.evaluate and script.callFunction to indicate either success or exception results (Firefox bug 1803599).

Marionette

• The cache for known nodes (element and shadow root references) has been moved from the parent to the web content process following recent WebDriver classic changes (Firefox bug 1692468).

• Improved the JSON serialization and deserialization algorithms to be compliant with the WebDriver classic specification (Firefox bug 1794078).

Changes for add-on developers

• Added the "webRequestFilterResponse" API permission. This permission provides access to webRequest.filterResponseData. This permission can be provided as an optional permission. See webRequest.filterResponseData for more information on using this permission (Firefox bug 1809235).
• The defaultZoomFactor property of tabs.ZoomSettings now returns the value of the default zoom factor setting (Firefox bug 1772166)