A webcam & microphone JS tester library that you can put in front of your WebRTC or MediaRecorder web app to diagnose any possible issues (the presence of getUserMedia, secure context, required devices, policies blocking device access, supported resolutions, etc.). It also primes your users’ OS/browser permissions before they get to the real app.

https://github.com/addpipe/webcam-tester

Live demo @ https://addpipe.com/webcam-tester/