<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script type="text/javascript">
function draw(id){
var convas = document.getElementById(id);
if(canvas == null){
return false;
}
var context = canvas.getContext('2d');
context.fillStyle = '#eeeeff';
context.fillRect(0,0,400,300);
for(var i=0;i<10;i++){
context.beginPath();
context.arc(i*25,i*25,i*10,0,Math.PI*2,true);
context.closePath();
context.fillStyle = 'rgba(255,0,0,0.25)';
context.fill();
}
}
</script>
</head>
<body onload="draw('canvas');">
<canvas id="canvas" width="400" height="300"></canvas>
</body>
</html>