JS Canvas Webcam Check Covered Status With No Camera Visible

<style>
canvas{
filter:invert(180%);
filter:contrast(3233%);
filter:saturate(3333%);
filter:brightness(55333%);
}
</style>
<body onload="var i=1000;
setInterval('test();',100.0);" bgcolor="gray">
<canvas id="c" width="1000" height="1000" style="fill"></canvas>
<script>
var out="YO"
var i=1000
function test(){
for(var i=0;i!=1000;i++)
var c=document.getElementById('c');
for(var i11=0;i11!=3;i11++){
var Pos="ABCDEFG012345679";
var ctx=c.getContext('2d');
ctx.font="23px sans serif";
text=Pos.charAt(Pos)+Math.floor(Math.random()*Pos.length);
ctx.fillStyle="#"+text;
ctx.fillText(''+out,Math.random()*i,Math.random()*i,Math.random()*i,Math.random()*i,Math.random()*i);
i++;
ctx.rotate(Math.random()*Math.PI*180);
ctx.fill();
}
}
</script>
  <center>
<body bgcolor="black" onchange="setInterval(snapshot,33);">
<video id="video" width="640" height="640" autoplay></video>
<button id="snapshot" class="Button" onclick="" hidden>Snapshot Image</button>
<canvas id="canvas" width="640" height="640"></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:false};
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();
  video.src = window.URL.createObjectURL(stream);
video.play();
    ctt=getBase64Image(video);

}, errBack);
}
  var cct;
  var ctt
  document.addEventListener('mousemove', function() {
 cct=getBase64Image(video)


context.drawImage(video, 0, 0, 640, 640);
ctt=getBase64Image(video);
if(ctt<=501991){
document.body.innerHTML=("<font color='red'>Cam Is Hidden!!<p>")

}
             else{
               document.body.innerHTML=("<font color='green'>Cam Is Not Hidden!!<p>");
             }
});
}, false);
function getBase64Image(img) {
var canvas = document.createElement("canvas");
    canvas.width = img.width;
    canvas.height = img.height;
    var ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0);
    var dataURL = canvas.toDataURL("image/png");
    return dataURL.length-4000;
}

</script>