Firefox 133 for developers

This article provides information about the changes in Firefox 133 that affect developers. Firefox 133 is the current Beta version of Firefox and ships on November 26, 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)

WebDriver BiDi

  • Added support for the url argument for the network.continueRequest command, allowing requests to be transparently redirected to another URL (Firefox bug 1898158).
  • Updated browsingContext.print to throw an InvalidArgumentError when used with incorrect dimensions (Firefox bug 1886382).
  • Fixed script.evaluate and script.callFunction to allow the use of document.open in sandbox realms (Firefox bug 1918288).
  • Fixed a bug where the browsingContext.load event might contain the wrong navigation ID if a same-document navigation occurred during the main navigation (Firefox bug 1922327).
  • Fixed another edge case where commands could fail with an UnknownError due to navigation (Firefox bug 1923899).

Marionette

  • Updated Marionette to better handle window positioning on Linux with Wayland (Firefox bug 1857571).
  • Fixed a bug that could leave an empty style attribute on an element when trying to click or clear it (Firefox bug 1922709).
  • Updated the error message sent for UnexpectedAlertOpen errors to include the text of the corresponding alert (Firefox bug 1924469).

Changes for add-on developers

Removals

Other

Experimental web features

These features are newly shipped in Firefox 133 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.

  • contenteditable plaintext-only value: dom.element.contenteditable.plaintext-only.enabled.

    The plaintext-only value of the contenteditable global attribute indicates that the element is editable; rich text formatting is disabled and any formatting in pasted text is automatically stripped. (Firefox bug 1922723.)

Older versions