Firefox 93 for developers
=========================

This article provides information about the changes in Firefox 93 that will affect developers. Firefox 93 was released on October 5, 2021.

**Note:** See also Lots to see in Firefox 93 on Mozilla Hacks.

Changes for web developers
--------------------------

### HTML

* The ARIA `meter` role has been implemented (Firefox bug 1727616).
* The UI for `<input type="datetime-local">` has been implemented. (Firefox bug 1283388).
### CSS

* The `small-caps` keyword is now supported for the `font-synthesis` property (Firefox bug 1706080).
### JavaScript

* Class `static` initialization blocks are now supported, allowing more flexible initialization of `static` properties (Firefox bug 1725689).
* The properties `imageOrientation` and `premultiplyAlpha` can be passed to the method `createImageBitmap()` using the `options` object (Firefox bug 1367251).
* `Intl.supportedValuesOf()` is now supported, allowing code to enumerate values supported by an implementation, This might be used, for example, to download a polyfill for just the missing category of values (Firefox bug 1670033).
### HTTP

* The SHA-256 algorithm is now supported for HTTP Authentication using digests. This allows much more secure authentication than previously available using the MD5 algorithm (Firefox bug 472823).
* The default HTTP `ACCEPT` header for *images* changed to: `image/avif,image/webp,*/*` (following addition of support for the AVIF image format). (Firefox bug 1682995).
### APIs

* `ElementInternals.shadowRoot` and `HTMLElement.attachInternals` are now supported (Firefox bug 1723521).
* The value `device-pixel-content-box` is now supported for `ResizeObserver.Observe()` (Firefox bug 1587973).
* The `reportError()` global function is now supported, allowing scripts to report errors to the console or global event handlers, emulating an uncaught JavaScript exception (Firefox bug 1722448).

#### Events

* The `onsecuritypolicyviolation` global event handler property is now supported.
 This can be used to assign a handler for processing `securitypolicyviolation` events fired when there is a Content Security Policy violation (Firefox bug 1727302).
* The `onslotchange` event handler property is now supported on `HTMLSlotElement` and `ShadowRoot`.
 This can be used to assign a handler for processing `slotchange` events, which are fired on `<slot>` elements when the node(s) contained in the slot change (Firefox bug 1501983).

#### Removals

* `KeyboardEvent.initKeyEvent()` has been moved behind the preference `dom.keyboardevent.init_key_event.enabled` and is disabled by default.
 The method is not present in any current specification or supported in other current browsers (Firefox bug 1717760).
### WebDriver conformance (Marionette)

* Fixed a bug which caused `WebDriver:Print` to fail for large documents (Firefox bug 1721982).
Changes for add-on developers
-----------------------------

* Sidebars are now included in `extension.getViews` when `windowId` is specified (Firefox bug 1612390).
Other
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* Support for AVIF images is now enabled by default (Firefox bug 1682995).
 This format has excellent compression and no patent restrictions (it was developed by the Alliance for Open Media).
 Firefox can display still images, with colorspace support for both full and limited range colors, and image transforms for mirroring and rotation.
 The preference image.avif.compliance\_strictness can be used to adjust the compliance strictness with the specification. Animated images are not supported.
Older versions
--------------

* Firefox 92 for developers
* 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