h5s2.2.5
by lozenlin
HTML
<canvas id="can" width="400" height="300"></canvas>
JavaScript
var ctx = can.getContext("2d");
var width = can.width,
height = can.height;
var xOff = width * 0.5 + 5,
yOff = height * 0.5 + 5;
for (var i = 0; i < 8; i++) {
ctx.beginPath();
ctx.arc(xOff, yOff, i*15, 0, Math.PI*2, true);
ctx.closePath();
ctx.stroke();
}