Firefox 118 release notes for developers

Changes for web developers

HTML

• The <search> element is now supported. The <search> element is a group element that serves to contain all the elements used in a search or filtering operation (Firefox bug 1824121).

CSS

• The font-synthesis-position property and position value for font-synthesis shorthand property are now supported. These allow subscript and superscript typefaces to be disabled for fonts that do not have glyphs for them when using font-variant-position (Firefox bug 1849010).
• Multiple CSS math functions are now supported: abs(), sign(), round(), mod(), rem(), pow(), sqrt(), hypot(), log(), and exp() (Firefox bug 1814589).
• A new keyword from-font in the CSS property font-size-adjust enables picking the desired <font-metric> from the first available font (Firefox bug 1708240).
• The CSS property transform-box now supports the values content-box and stroke-box. For the reference box, the content-box value uses the content box and the stroke-box value uses the stroke bounding box that contains an SVG's shape (Firefox bug 1819464).
• The CSS property font-size-adjust supports the keyword from-font that enables picking the desired <font-metric> from the first available font (Firefox bug 1708240).

JavaScript

No notable changes.

HTTP

• The HTTP Permissions-Policy header's publickey-credentials-get directive is now supported, which can be used to enable the Web Authentication API interface for retrieving public-key credentials in a cross-origin iframe (Firefox bug 1460986).

MathML

• The <semantics> and <maction> elements only render the first child element by default now. The mathml.legacy_maction_and_semantics_implementations.disabled preference has been removed (Firefox bug 1788223).
• All values of the mathvariant attribute other than normal are now deprecated. Additionally, the attribute's use is now limited to the <mi> element (Firefox bug 1845461).

APIs

• The ⊞ Windows Logo key on Windows and the Command key on macOS now return a value of "Meta" for KeyboardEvent.key, instead of "OS", and KeyboardEvent.code returns MetaLeft/MetaRight instead of OSLeft/OSRight (Firefox bug 1232918).
• The RTCRtpTransceiver.currentDirection and RTCRtpTransceiver.direction properties now support the "stopped" value for indicating whether a transceiver has stopped. This value should now be used instead of the deprecated RTCRtpTransceiver.stopped property (Firefox bug 1568296).
• The array returned by RTCPeerConnection.getTransceivers() now omits stopped transceivers. Similarly, RTCPeerConnection.getReceivers() and RTCPeerConnection.getSenders() omit the receivers and senders associated with a stopped transceiver (Firefox bug 1568296).
• The TextMetrics.emHeightDescent and TextMetrics.emHeightAscent properties are now supported (Firefox bug 1841692).

WebDriver conformance (WebDriver BiDi, Marionette)

General

• Fixed an internal race condition for Android that caused the returned user prompt text to be empty for both WebDriver BiDi and Marionette (Firefox bug 1848167).
• Both the WebDriver:PerformActions command in Marionette and the browsingContext.performActions command in WebDriver BiDi failed to correctly scroll for a wheel input source in environments that have a high-resolution display connected (Firefox bug 1849229).

WebDriver BiDi

• Added the browsingContext.activate command that allows users to bring the given background tab into foreground (Firefox bug 1841004).
• Added the browsingContext.handleUserPrompt command that allows users to accept or dismiss an open user prompt of type alert, confirm, or prompt (Firefox bug 1824197).
• Added the browsingContext.userPromptOpened event that is emitted when a user prompt of type alert, confirm, or prompt was opened (Firefox bug 1824224).
• Added a type field to the JSON payload that is returned to clients for identifying event messages or the success state of a command, which can be either success or error (Firefox bug 1844009).

Marionette

• Added support for all the Web Authentication extension commands, which allow users to authenticate themselves by Public Key Credentials (Firefox bug 1846574)

Changes for add-on developers

Removals

• Support for browser_style in the manifest keys action, options_ui, page_action, and sidebar_action for Manifest V3 extensions has been removed (Firefox bug 1830711). See Browser Styles' Manifest v3 migration for information about transitioning from browser_style in Manifest V3 extensions.