<head>
<meta charset=utf-8 />
</head>
<body onload="draw();">
<canvas id="circle" width="500" height="500" style="border:1px solid grey"></canvas>
<script>
function draw()
{
var canvas = document.getElementById('circle');
var ctx = canvas.getContext('2d');
var X = canvas.width / 2;
var Y = canvas.height / 2;
var R = 1500;
ctx.beginPath();
ctx.arc(X,Y, R, 0, 2 * Math.PI, false);
ctx.lineWidth = 3;
ctx.strokeStyle = '#FF0000';
ctx.stroke();
let idinterval = setInterval(function(){
ctx.fillRect(0, 0, 500, 500);
R = Math.floor(Math.random()*250)+25;
ctx.arc(X,Y, R, 0,Math.PI*2, false);
ctx.stroke();
},100);
}
</script>
</body>
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