Firefox 146 release notes for developers (Beta)

Changes for web developers

CSS

• The contrast-color() function is now supported. This function takes a <color> value and returns a contrasting color that ensures at least WCAG AA minimum contrast. (Firefox bug 1682439).

• The <color> data type now supports the display-p3-linear color space. This space is similar to display-p3, except that it uses a linear-light transfer function and has no gamma-encoding, which allows for a higher precision in the colors displayed. (Firefox bug 1996318).

• The text-decoration-inset property is now supported, which enables adjusting the start and end points of an element's text-decoration so it can be shortened, lengthened, or have its position shifted with respect to the rendered text. (Firefox bug 1979915, Firefox bug 1997157, Firefox bug 1993043).

• The @scope at-rule is now supported by default. This enables you to select elements in specific DOM subtrees, targeting elements precisely without writing overly-specific selectors that are hard to override, and without coupling your selectors too tightly to the DOM structure. (Firefox bug 1991105).

• The legacy -webkit-fill-available keyword is now supported as a value for the CSS width and height properties to improve web compatibility. This keyword is an alias for the recently-standardized stretch keyword (i.e., width: stretch and height: stretch), which isn't yet supported in Firefox. (Firefox bug 1988938, Firefox bug 1789477).

JavaScript

• WeakMap and WeakSet now accept Symbol objects as keys, except for those that are registered. (Firefox bug 1966745).

APIs

• SubtleCrypto.importKey() now allows you to import keys defined as compressed elliptic curve points when using the ECDSA or ECDH algorithms. (Firefox bug 1971499).

Changes for add-on developers

• browsingData.removeLocalStorage and browsingData.remove (when localStorage is set in browsingData.DataTypeSet) now delete objects from sessionStorage. (Firefox bug 1886894)

Experimental web features

These features are shipping in Firefox 146 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 page.

• Navigation API (Nightly): dom.navigation.webidl.enabled

  Nightly builds now support the Navigation API, which provides the ability to initiate, intercept, and manage browser navigation actions. It can also examine an application's history entries. This is a successor to previous web platform features such as the History API and window.location, which solves their shortcomings and is specifically aimed at the needs of single-page applications (SPAs). (Firefox bug 1979288).