mozallowfullscreen attribute on <iframe> is no longer supported


Categories: HTML

Releases: Firefox 81


Firefox 81 has dropped the support for the mozallowfullscreen attribute on the <iframe> element. The unprefixed allowfullscreen attribute has been available since Firefox 18.

According to the changelog, mozallowfullscreen had actually been broken since Firefox 74 because newly implemented Feature Policy didn’t take it into account. The bug was fixed with Firefox 80, but the prefixed attribute is now gone in favour of the current standard.

To support older browsers, you still have to use the allowfullscreen attribute together with allow="fullscreen".

How can I test this?

This change can be tested with the compatibilty checker in our Firefox Developer Tools extension. Get it today!