Firefox 92 for developers

This article provides information about the changes in Firefox 92 that will affect developers. Firefox 92 was released on September 7, 2021.

No changes

• The keywords avoid-page and avoid-column are now supported for the break-inside property (bug 1722945).
• The two-value syntax for the font-size-adjust property is now supported (bug 1720131).
• The @font-face/size-adjust descriptor is now supported (bug 1720131).
• The CSS accent-color property has been implemented (bug 1722031).
• The system-ui value is now supported for the font-family property (bug 1226042).

• Object.hasOwn() can be used to test whether a property was defined on an object or inherited (bug 1721149).
• The default 5MB storage quota is now available to each origin. The quota previously applied to an entire domain group (also known as eTLD+1 domain; e.g., *.wikipedia.org). (bug 1064466).
• Storage quotas for Window.localStorage are now shared with IndexedDB API and Cache API (bug 742822).

• Firefox will automatically upgrade an HTTP request to HTTPS when a usable HTTPS RR is available. It will also use information provided in an HTTPS RR to optimize the process of establishing HTTPS connections⁠—this is conceptually similar to using the Alt-Svc header. (bug 1721132).

• The disabledFeatures static property has been implemented for Custom Elements (bug 1723396).

DOM

• The Imperative Slotting API (part of the Shadow Dom API) Has been implemented. (bug 1705141)
• You can now monitor for changes to text selections in <input> or <textarea> by listening for selectionchange events in HTMLInputElement and HTMLTextAreaElement, respectively (bug 1648944).

Media, WebRTC, and Web Audio

• Access to audio output devices, like speakers and headphones, is now protected by the speaker-selection feature policy (bug 1577199).

• Improved support for the webSocketUrl capability, which now returns the WebDriver BiDi websocket URL if true was passed and if BiDi is supported. (bug 1692984).

• Support for cookieStoreId is added to downloads.download, downloads.DownloadQuery, and downloads.DownloadItem. The addition to the types downloads.DownloadQuery and downloads.DownloadItem provides support in downloads.search and downloads.erase. Web extensions can now associate downloads with specific cookie stores, such as container tabs (contextual identities). (bug 1669566)