📃 November 2023 release notes

Newly available

The following features are newly available:

Clip path boxes: The fill-box, stroke-box, and view-box values for clip-path set an edge of the element's box to use as the clipping shape.
lh unit: The CSS lh unit corresponds to the requested line height, the computed value of the line-height property. Some lines may be higher than this based on their content.
rlh unit: The rlh CSS length unit is a font-relative length relative to the line height of root element.
User activation: The navigator.userActivation API reveals whether the user has interacted with the page through an "activation" gesture such as a click, tap, or key press. User activation gated APIs (such as the fullscreen API) fail without user interaction, and this API allows you to predict such a failure.
:user-valid and :user-invalid: The :user-valid and :user-invalid pseudo-classes match form controls that have been marked as valid or invalid based on their validation constraints.

The following features are now available in Edge:

Beforeunload: The beforeunload event is fired when the current window is about to be unloaded. Typically this is used to display a dialog to confirm if users really want to leave the page when there is unsaved data that would be lost.
prefers-reduced-transparency media query: The prefers-reduced-transparency CSS media query sets styles based on whether the user prefers to reduce the amount of transparent effects on their device, for example to improve contrast and legibility.
Promise.withResolvers(): The Promise.withResolvers() static method is an alternative to the Promise() constructor that returns both the promise and resolution functions. You can use this to access resolve and reject outside the scope of the executor function.
Garbage collection (WebAssembly): Garbage collection tracks references for better memory management with garbage-collected languages running in WebAssmbly.
Typed function references (WebAssembly): A typed function reference can be called directly.
word-break: auto-phrase: The word-break: auto-phrase CSS declaration specifies that wrapping should occur at natural phrase boundaries, especially in CJK languages.

The following features are now available in Firefox:

Global privacy control: The Sec-GPC request header indicates that the user does not consent to a website or service selling or sharing their personal information with third parties.
Inert elements: The inert HTML attribute marks an element and its descendants as non-interactive. Inert elements don't get focus or fire click events.
light-dark(): The light-dark() CSS function accepts two colors and uses one depending on the current color scheme.
Vertical form controls: The writing-mode CSS property orients form elements (such as radio buttons, progress bars, or select menus) vertically when the writing mode is vertical-lr or vertical-rl. The direction CSS property sets whether inputs flow from top to bottom or bottom to top.
Garbage collection (WebAssembly): Garbage collection tracks references for better memory management with garbage-collected languages running in WebAssmbly.
Typed function references (WebAssembly): A typed function reference can be called directly.

The following features are now available in Firefox for Android:

Inert elements: The inert HTML attribute marks an element and its descendants as non-interactive. Inert elements don't get focus or fire click events.
light-dark(): The light-dark() CSS function accepts two colors and uses one depending on the current color scheme.
Vertical form controls: The writing-mode CSS property orients form elements (such as radio buttons, progress bars, or select menus) vertically when the writing mode is vertical-lr or vertical-rl. The direction CSS property sets whether inputs flow from top to bottom or bottom to top.
Garbage collection (WebAssembly): Garbage collection tracks references for better memory management with garbage-collected languages running in WebAssmbly.
Typed function references (WebAssembly): A typed function reference can be called directly.