Firefox 92 release notes for developers

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

[!NOTE] See also Time for a review of Firefox 92 on Mozilla Hacks.

Changes for web developers

HTML

No changes

CSS

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

JavaScript

• {{jsxref("Object.hasOwn()")}} can be used to test whether a property was defined on an object or inherited (Firefox 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 {{Glossary("registrable domain")}}; e.g., *.wikipedia.org). (Firefox bug 1064466).
• Storage quotas for {{domxref("Window.localStorage")}} are now shared with IndexedDB API and {{domxref("Cache")}} (Firefox bug 742822).

HTTP

• Firefox will automatically upgrade an HTTP request to HTTPS when a usable {{Glossary("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 {{HTTPHeader("Alt-Svc")}} header. (Firefox bug 1721132).

APIs

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

DOM

• The Imperative Slotting API (part of the Shadow DOM API) Has been implemented. (Firefox bug 1705141)
• You can now monitor for changes to text selections in {{HTMLElement("input")}} or {{HTMLElement("textarea")}} by listening for selectionchange events in {{domxref("HTMLInputElement.selectionchange_event", "HTMLInputElement")}} and {{domxref("HTMLTextAreaElement/selectionchange_event", "HTMLTextAreaElement")}}, respectively (Firefox 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 (Firefox bug 1577199).

WebDriver conformance (Marionette)

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

Changes for add-on developers

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