Firefox 126 for developers

This article provides information about the changes in Firefox 126 that affect developers. Firefox 126 is the current Beta version of Firefox and ships on May 14, 2024.

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)

General

WebDriver BiDi

Marionette

Changes for add-on developers

  • The commands.onCommand event now passes the tab argument to the event listener. This enables extensions to apply a triggered shortcut to the page in which it was issued, without the need to call the tabs.query() method (Firefox bug 1843866).
  • The runtime.MessageSender type now includes the origin property. This enables message or connection requests to see the page or frame that opened the connection. This is useful for identifying if the origin can be trusted if it isn't apparent from the URL (Firefox bug 1787379).

Removals

Other

Experimental web features

These features are newly shipped in Firefox 126 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