Firefox 151 release notes for developers (Beta)
This article provides information about the changes in Firefox 151 that affect developers. Firefox 151 is the current Beta version of Firefox and ships on May 19, 2026.
Note: The release notes for this Firefox version are still a work in progress.
Changes for web developers
APIs
- The
options.keyboardLockproperty can now be passed as an option toElement.requestFullscreen(), allowing websites to request keyboard lock when the element is displayed in fullscreen mode. This prevents the Esc key from causing the element to leave fullscreen (instead, a long-press is required), and some formerly-reserved browser hotkeys are allowed to be default-prevented. (Firefox bug 2032302).
Changes for add-on developers
Experimental web features
These features are shipping in Firefox 151 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.