mdn · zfox23 · Dec 19, 2023 · Dec 19, 2023
@@ -6,28 +6,22 @@ page-type: firefox-release-notes
 
 {{FirefoxSidebar}}
 
-This article provides information about the changes in Firefox 121 that affect developers. Firefox 121 is the current [Beta version of Firefox](https://www.mozilla.org/en-US/firefox/channel/desktop/#beta) and ships on [December 19, 2023](https://whattrainisitnow.com/release/?version=121).
+This article provides information about the changes in Firefox 121 that affect developers. Firefox 121 was released on [December 19, 2023](https://whattrainisitnow.com/release/?version=121).
 
 ## Changes for web developers
 
-### Developer Tools
-
 ### HTML
 
 - [Lazy loading](/en-US/docs/Web/Performance/Lazy_loading) of `<iframes>` is now supported, allowing developers to hint that particular `<iframe>`s should only be loaded when (and if) they become visible. This can speed up initial load time by reducing the resources that need to be fetched on page load (some `<iframes>` may not need to be fetched at all).
   The hint can be provided via the [`loading`](/en-US/docs/Web/HTML/Element/iframe#loading) attribute on the [`<iframe>`](/en-US/docs/Web/HTML/Element/iframe) element, or in JavaScript using {{domxref("HTMLIFrameElement.loading")}}.
   ([Firefox bug 1622090](https://bugzil.la/1622090)).
 
-#### Removals
-
 ### CSS
 
 - The {{CSSXRef("text-wrap")}} property has been updated with support for the values `balance` and `stable`. The `balance` value is used for short blocks of content, such as headings, and will make sure that the content is balanced and easy to read when spread over multiple lines. The `stable` value makes sure that editable content does not reflow while the user is editing it ([Firefox bug 1731541](https://bugzil.la/1731541)).
 - The {{cssxref(":has", ":has()")}} selector, commonly referred to as the _parent selector_, is now supported. It allows developers to apply styles to an element based on related elements, e.g. `li:has(ul)` will match a list which contains a sub-list, or `h1:has(+ p)` will match a heading with a paragraph directly after it.
 - The [`text-indent`](/en-US/docs/Web/CSS/text-indent) CSS property now supports the [`each-line`](/en-US/docs/Web/CSS/text-indent#each-line) and [`hanging`](/en-US/docs/Web/CSS/text-indent#hanging) property values ([Firefox bug 784648](https://bugzil.la/784648)), allowing developers to more easily specify certain text indentation styles. Additionally, developers can now combine multiple `text-indent` property values for more creativity, e.g. `text-indent: 3em hanging each-line`.
 
-#### Removals
-
 ### JavaScript
 
 - The {{jsxref("Promise.withResolvers()")}} static method is now supported. This exposes the `resolve` and `reject` callback functions in the same scope as the returned {{jsxref("Promise")}}, allowing code that resolves or rejects the promise to be defined after its construction ([Firefox bug 1845586](https://bugzil.la/1845586)).
@@ -49,56 +43,26 @@ This article provides information about the changes in Firefox 121 that affect d
   - `YYYY-M-DD` and `YYYY-MM-D` are no longer assumed GMT as an ISO date `YYYY-MM-DD` would be ([Firefox bug 1783731](https://bugzil.la/1783731)).
   - Milliseconds for all formats are truncated after 3 digits, rather than being rounded ([Firefox bug 746529](https://bugzil.la/746529)).
 
-#### Removals
-
-### SVG
-
-#### Removals
-
-### HTTP
-
-#### Removals
-
-### Security
-
-#### Removals
-
 ### APIs
 
 - The {{domxref("WebTransportSendStream.sendOrder", "sendOrder")}} property of the {{domxref("WebTransportSendStream")}} interface is now supported, allowing the relative priority of outgoing [WebTransport API](/en-US/docs/Web/API/WebTransport_API) _bidirectional_ streams to be read and changed after the stream is created. Note that this cannot be used to modify the priority of unidirectional streams, as Firefox implements them as {{domxref("WritableStream")}} instead of {{domxref("WebTransportSendStream")}}. (For more information see [Firefox bug 1853444](https://bugzil.la/1853444).)
 
-#### DOM
-
-#### Media, WebRTC, and Web Audio
-
-#### Removals
-
 ### WebAssembly
 
 - WebAssembly now supports tail call optimization via new `return_call` and `return_call_indirect` alternatives to the [`call`](/en-US/docs/WebAssembly/Reference/Control_flow/call) instruction. This improves performance, reduces stack space usage, and enhances compatibility with programming languages that use tail calls. ([Firefox bug 1858855](https://bugzil.la/1846789)).
 
-#### Removals
-
 ### WebDriver conformance (WebDriver BiDi, Marionette)
 
 #### WebDriver BiDi
 
 - Added the [`browsingContext.contextDestroyed`](https://w3c.github.io/webdriver-bidi/#event-browsingContext-contextDestroyed) event that is emitted when a browsing context is discarded ([Firefox bug 1694390](https://bugzil.la/1694390)).
-
 - Added support for the `userActivation` parameter for the [`script.callFunction`](https://w3c.github.io/webdriver-bidi/#command-script-callFunction) and [`script.evaluate`](https://w3c.github.io/webdriver-bidi/#command-script-evaluate) commands which allows evaluating JavaScript while emulating the user action. ([Firefox bug 1845488](https://bugzil.la/1845488)).
-
 - Added support for the `defaultValue` field for the [`browsingContext.userPromptOpened`](https://w3c.github.io/webdriver-bidi/#event-browsingContext-userPromptOpened) event that allow users to retrieve the default value of prompts ([Firefox bug 1851761](https://bugzil.la/1851761)).
-
 - Renamed the `viewportOptions` parameter for the [`browsingContext.captureScreenshot`](https://w3c.github.io/webdriver-bidi/#command-browsingContext-captureScreenshot) command to `boxOptions` ([Firefox bug 1859258](https://bugzil.la/1859258)).
-
 - Removed the `scrollIntoView` parameter for the [`browsingContext.captureScreenshot`](https://w3c.github.io/webdriver-bidi/#command-browsingContext-captureScreenshot) command, in favor of the `origin` parameter below ([Firefox bug 1862649](https://bugzil.la/1862649)).
-
 - Added support for the `origin` parameter for the [`browsingContext.captureScreenshot`](https://w3c.github.io/webdriver-bidi/#command-browsingContext-captureScreenshot) command which allows defining the origin and bounds of the screenshot. The accepted values are `"document"` and `"viewport"` ([Firefox bug 1840999](https://bugzil.la/1840999)).
-
 - When serializing `Window` objects, the serialized value now contains a `context` property set to the context id for the `Window` object which can also be exchanged with Marionette to reference specific windows and frames ([Firefox bug 1841049](https://bugzil.la/1841049)).
-
 - Fixed a bug where serialization of a Node nested in a data structure (array, map, etc.) would fail ([Firefox bug 1861000](https://bugzil.la/1861000)).
-
 - Fixed a bug where the [`browsingContext.navigate`](https://w3c.github.io/webdriver-bidi/#command-browsingContext-navigate) command could return an incorrect navigation id ([Firefox bug 1861655](https://bugzil.la/1861655)).
 
 #### Marionette
@@ -116,10 +80,6 @@ These features are newly shipped in Firefox 121 but are disabled by default. To
 
 ## Changes for add-on developers
 
-### Removals
-
-### Other
-
 - Fixed a bug that resulted in background pages not starting when a manifest.json `background` key contains `service_worker` and `scripts` declarations ([Firefox bug 1860304](https://bugzil.la/1860304)).
 
   > **Note:** Incidentally, a change in Chrome 121 sees the `scripts` property ignored when specified with the `service_worker` property. Previously, Chrome refused to load extensions containing both properties ([Chromium bug 1418934](https://crbug.com/1418934)).

@@ -6,7 +6,7 @@ page-type: firefox-release-notes
 
 {{FirefoxSidebar}}
 
-This article provides information about the changes in Firefox 122 that affect developers. Firefox 122 is the current [Nightly version of Firefox](https://www.mozilla.org/en-US/firefox/channel/desktop/#nightly) and ships on [January 23, 2024](https://whattrainisitnow.com/release/?version=122).
+This article provides information about the changes in Firefox 122 that affect developers. Firefox 122 is the current [Beta version of Firefox](https://www.mozilla.org/en-US/firefox/channel/desktop/#beta) and ships on [January 23, 2024](https://whattrainisitnow.com/release/?version=122).
 
 ## Changes for web developers
 
@@ -60,6 +60,10 @@ This article provides information about the changes in Firefox 122 that affect d
 
 ### Other
 
+## Experimental web features
+
+These features are newly shipped in Firefox 122 but are disabled by default. To experiment with them, search for the appropriate preference on the `about:config` page and set it to `true`. You can find more such features on the [Experimental features](/en-US/docs/Mozilla/Firefox/Experimental_features) page.
+
 ## Older versions
 
 {{Firefox_for_developers(121)}}
@@ -0,0 +1,69 @@
+---
+title: Firefox 123 for developers
+slug: Mozilla/Firefox/Releases/123
+page-type: firefox-release-notes
+---
+
+{{FirefoxSidebar}}
+
+This article provides information about the changes in Firefox 123 that affect developers. Firefox 123 is the current [Nightly version of Firefox](https://www.mozilla.org/en-US/firefox/channel/desktop/#nightly) and ships on [February 20, 2024](https://whattrainisitnow.com/release/?version=123).
+
+## Changes for web developers
+
+### Developer Tools
+
+### HTML
+
+#### Removals
+
+### CSS
+
+#### Removals
+
+### JavaScript
+
+#### Removals
+
+### SVG
+
+#### Removals
+
+### HTTP
+
+#### Removals
+
+### Security
+
+#### Removals
+
+### APIs
+
+#### DOM
+
+#### Media, WebRTC, and Web Audio
+
+#### Removals
+
+### WebAssembly
+
+#### Removals
+
+### WebDriver conformance (WebDriver BiDi, Marionette)
+
+#### WebDriver BiDi
+
+#### Marionette
+
+## Changes for add-on developers
+
+### Removals
+
+### Other
+
+## Experimental web features
+
+These features are newly shipped in Firefox 123 but are disabled by default. To experiment with them, search for the appropriate preference on the `about:config` page and set it to `true`. You can find more such features on the [Experimental features](/en-US/docs/Mozilla/Firefox/Experimental_features) page.
+
+## Older versions
+
+{{Firefox_for_developers(122)}}