Firefox 136 for developers

This article provides information about the changes in Firefox 136 that affect developers. Firefox 136 is the current Beta version of Firefox and ships on March 4, 2025.

Changes for web developers

Developer Tools

HTML

  • The autocorrect global attribute allows autocorrection in editable text elements including: most kinds of text <input> elements, <textarea> elements, and elements that have the contenteditable attribute set. The specific autocorrection behavior depends on the user agent and underlying OS. (Firefox bug 1927977).

Removals

CSS

Removals

JavaScript

Removals

SVG

Removals

HTTP

  • The Referer HTTP header is now sent in requests following a page refresh that redirects to a new page (if permitted by the Referrer-Policy), and document.referrer will be set to the referrer URL after navigating. The page refresh may be triggered by the Refresh response header, or equivalent <meta> in markup (for example <meta http-equiv="refresh" content="3;url=https://www.mozilla.org" />). Note that same-page refreshes are treated as same-page navigation to a page fragment: since the page isn't re-requested, Referer isn't sent. (Firefox bug 1928291)

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

Removals

Other

Experimental web features

These features are newly shipped in Firefox 136 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.

  • Error.captureStackTrace(): javascript.options.experimental.error_capture_stack_trace. The Error.captureStackTrace() static method installs stack trace information on a provided object as the Error.stack property. Its main use case is to install a stack trace on a custom error object that does not derive from the Error interface. (Firefox bug 1886820).
  • Clear-Site-Data: cache: privacy.clearSiteDataHeader.cache.enabled. The Clear-Site-Data header can be used with the cache or * directives to clear the browser cache. (Firefox bug 1942272).

Older versions