<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style>
canvas{
border: 1px dashed black;
}
</style>
<script>
window.onload = function(){
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext("2d");
context.translate(100,100);//平移
var cop = 10;//试着减小或增大cop的值观察图案变化
for(var i = 1; i<cop; i++){
context.rotate(2*Math.PI*1/(cop-1));//旋转
context.rect(0,0,60,60);//画矩形
}
context.strokeStyle = "red";
context.stroke(); }
</script>
</head>
<body>
<canvas id="myCanvas" width="300" height="200">
</canvas>
</body>
</html>