How to access UserMedia

if (navigator.mediaDevices.getUserMedia === undefined) {
	navigator.mediaDevices.getUserMedia = function(constraints) {
	 var getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia;
	 
	 if (!getUserMedia) {
		return Promise.reject(new Error('getUserMedia is not implemented in this browser'));
	 }

	 return new Promise(function(resolve, reject) {
		getUserMedia.call(navigator, constraints, resolve, reject);
	 });
	}
 }
 
 navigator.mediaDevices
	.getUserMedia({ video: true })
	.then(function(stream) {
	 var vid = document.createElement('video');
	 vid.src = stream;
	 console.log(vid);
	})
	.catch(function(err) {
	 console.log(err.name + ": " + err.message);
	}
);