<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
Your browser does not support the HTML5 canvas tag.
</canvas>
<script>
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
// 红色矩形
ctx.beginPath();
ctx.lineWidth="6";
ctx.strokeStyle="red";
ctx.rect(5,5,290,140);
ctx.stroke();
// 绿色矩形
ctx.lineWidth="4";
ctx.strokeStyle="green";
ctx.rect(30,30,50,50);
// 蓝色矩形
ctx.lineWidth="10";
ctx.strokeStyle="blue";
ctx.rect(50,50,150,80);
</script>
</body>
</html>