Firefox 125 for developers

This article provides information about the changes in Firefox 125 that affect developers. Firefox 125 is the current Beta version of Firefox and ships on April 16, 2024.

Changes for web developers

Developer Tools

HTML

Removals

CSS

  • The align-content property has been updated to work with display: block; layouts. This brings all the layout positions from flex and grid to block, enabling developers to align block-level elements without converting their container to a flex or grid container. (Firefox bug 1882853).
  • The CSS property transform-box now supports the values content-box and stroke-box. For the reference box, the content-box value uses the content box and the stroke-box value uses the stroke bounding box that contains an SVG's shape (Firefox bug 1868374).

Removals

JavaScript

  • Intl.Segmenter is now supported, allowing developers to perform locale-sensitive text segmentation of a string. This enables, for example, splitting a string into words in languages that don't use spaces to separate them: Intl.Segmenter("ja-JP", { granularity: "word" }). You can also split strings into graphemes or sentences. (Firefox bug 1423593, Firefox bug 1883914.)

Removals

SVG

Removals

HTTP

Removals

Security

Removals

APIs

DOM

Media, WebRTC, and Web Audio

Removals

WebAssembly

Removals

WebDriver conformance (WebDriver BiDi, Marionette)

General

WebDriver BiDi

Changes for add-on developers

Removals

Other

Experimental web features

These features are newly shipped in Firefox 125 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.

Older versions