console
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95,50,40,0,2*Math.PI);
ctx.stroke();
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script class="jquery library" src="/js/sandbox/jquery/jquery-1.8.2.min.js" type="text/javascript"></script>
<title>RunJS 演示代码</title>
</head>
<body>
<canvas id="myCanvas" width="200" height="100" >
</canvas>
</body>
</html>