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                <h1>Common getUserMedia() Errors</h1>
<p>JS code that handles the most common errors thrown by the <code>getUserMedia()</code> promise on both Chrome and Firefox.</p>
<video controls autoplay></video>


                html, body{
  height: 100%;
  overflow: hidden;
  width: 100%;


                var videoElement = document.querySelector('video');
var textarea = document.createElement('pre');

var constraints =  {
    video:true, audio:true

navigator.mediaDevices.getUserMedia(constraints).then(function success(stream) {
	/* do stuff */
  videoElement.srcObject = stream;
}).catch(function(err) {
    //log to console first
    //log to webpage as well
    textarea.innerHTML = textarea.innerHTML+""', err.message:'+err.message+', err.constraintName:'+err.constraintName+'<br>' ;
    /* handle the error */
    if ("NotFoundError" || == "DevicesNotFoundError" ){
        //required track is missing
    } else if ("NotReadableError" || == "TrackStartError" ){
         //webcam or mic are already in use
    } else if ("OverconstrainedError" || == "ConstraintNotSatisfiedError" ){
        //constraints can not be satisfied by avb. devices
    } else if ("NotAllowedError" || == "PermissionDeniedError" ){
        //permission denied in browser
    } else if ("TypeError" || == "TypeError" ){
        //empty constraints object       
    } else {
         //other errors