JS Canvas Audio & Video Self Monitor SRC V1

<center>
<body bgcolor="black">
<video id="video" width="640" height="480" autoplay></video>
<button id="snapshot" class="Button">Snapshot Image</button>
<canvas id="canvas" width="640" height="480"></canvas>
<script>
window.addEventListener("DOMContentLoaded", function() {
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var video = document.getElementById('video');
var mediaConfig =  { video: true,audio:true};
var errBack = function(e) {
console.log('An error has occurred!', e)
};
if(navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
navigator.mediaDevices.getUserMedia(mediaConfig).then(function(stream) {
video.src = window.URL.createObjectURL(stream);
video.play();
});
}
else if(navigator.getUserMedia) {
navigator.getUserMedia(mediaConfig, function(stream) {
video.src = stream;
video.play();
}, errBack);
} else if(navigator.webkitGetUserMedia) {
navigator.webkitGetUserMedia(mediaConfig, function(stream){
video.src = window.webkitURL.createObjectURL(stream);
video.play();
}, errBack);
} else if(navigator.mozGetUserMedia) {
navigator.mozGetUserMedia(mediaConfig, function(stream){
video.src = window.URL.createObjectURL(stream);
video.play();
}, errBack);
}
document.getElementById('snapshot').addEventListener('click', function() {
context.Image(video, 0, 0, 640, 480);
});
}, false);
</script>