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.

**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 `break-inside` property (Firefox bug 1722945).
* The two-value syntax for the `font-size-adjust` property is now supported (Firefox bug 1720131).
* The `@font-face/size-adjust` descriptor is now supported (Firefox bug 1720131).
* The CSS `accent-color` property has been implemented (Firefox bug 1722031).
* The `system-ui` value is now supported for the `font-family` property (Firefox bug 1226042).
### JavaScript

* `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 eTLD+1 domain; e.g., `*.wikipedia.org`). (Firefox bug 1064466).
* Storage quotas for `Window.localStorage` are now shared with IndexedDB API and `Cache API` (Firefox bug 742822).
### HTTP

* 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.
 (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 `<input>` or `<textarea>` by listening for `selectionchange` events in `HTMLInputElement` and `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 `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). (Firefox bug 1669566)
Older versions
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* Firefox 91 for developers
* Firefox 90 for developers
* Firefox 89 for developers
* Firefox 88 for developers
* Firefox 87 for developers
* Firefox 86 for developers
* Firefox 85 for developers
* Firefox 84 for developers
* Firefox 83 for developers
* Firefox 82 for developers
* Firefox 81 for developers
* Firefox 80 for developers
* Firefox 79 for developers
* Firefox 78 for developers
* Firefox 77 for developers
* Firefox 76 for developers
* Firefox 75 for developers
* Firefox 74 for developers
* Firefox 73 for developers
* Firefox 72 for developers
* Firefox 71 for developers
* Firefox 70 for developers
* Firefox 69 for developers
* Firefox 68 for developers
* Firefox 67 for developers
* Firefox 66 for developers
* Firefox 65 for developers
* Firefox 64 for developers
* Firefox 63 for developers
* Firefox 62 for developers
* Firefox 61 for developers