Detect Firefox support for screen sharing

问题

Firefox, since version 52, will support screen sharing via:

navigator.mediaDevices.getUserMedia({ video: { mediaSource: 'screen' }}) 
  .then(stream => { ... });

Check out this test page to see it in action.

I would like to know whether there is a way to detect whether a browser supports { mediaSource: 'screen' }?

I would like to only give the option to share the screen with users that have the ability to share. So I'd like to be able to feature detect this.

回答1:

a way to detect whether a browser supports { mediaSource: 'screen' }?

The pedantic answer is the following will tell you if the mediaSource constraint is supported:

console.log(!!navigator.mediaDevices.getSupportedConstraints().mediaSource);

Unfortunately, mediaSource is non-standard, and only implemented in Firefox. Firefox is as of this writing the only browser to enable screen-sharing without a plugin.

Chrome has a different non-standard API using chromeMediaSource available as a plug-in, using an older constraints syntax, but it (rightly) does not appear in the new getSupportedConstraints.

It's a bit of a mess still. Long-term browsers may end up implementing getDisplayMedia instead.

来源：https://stackoverflow.com/questions/46101264/detect-firefox-support-for-screen-sharing