<canvas id="ctx" width="300" height="300" border="1"></canvas>

<script type="text/javascript">
var canvas = document.getElementById("ctx");
var ctx = canvas.getContext("2d");

function resetCanvas(){
	ctx.clearRect(0, 0, canvas.width, canvas.height);
}

var frameno = 0;
var fps = 100;

function sequence1() {
	setTimeout(function () {
		resetCanvas();

		ctx.beginPath();
		ctx.arc(150, 150, 20+frameno*3, 0, 2*Math.PI, true);
		ctx.stroke();

		frameno = frameno + 1;

		/* RERUN */
		if(frameno > 50){
			frameno = 0;
		}
		sequence1();
	}, fps);
}

sequence1();
</script>