How to resolve "Allow attribute will take precedence over allowfullscreen" warning?

Question

Allow attribute will take precedence over 'allowfullscreen'.

I'm getting this warning message because I've added an iframe with both allow="fullscreen" and allowfullscreen.

allow doesn't seem to work in IE, Edge, or Firefox, according to https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe.

How can I resolve/silence this warning message in a cross-browser compatible way?

Here's a minimal snippet to reproduce the warning message in Chrome:

const iframe = document.createElement('iframe');
iframe.setAttribute('allowFullScreen', '');
iframe.setAttribute('allow', 'fullscreen');

Answer 1

Turns out swapping the order of those setAttribute lines silences the warning:

const iframe = document.createElement('iframe');
iframe.setAttribute('allow', 'fullscreen'); // must be 1st
iframe.setAttribute('allowFullScreen', '');