学习方法：
1.查看官网说明书
2.参考DEMO，编写实例
3.查看API，应用在项目中
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>Twojs</title>
<style></style>
</head>
<body>
<h2>第三方绘图工具库Two.js</h2>
<div id="box"></div>
<script src="js/two.js"></script>
<script>
//创建一个绘图对象type:Two.Types.svg和type:Two.Types.canvas
var options ={
width:800,
height:400,
type:Two.Types.svg
}
var two = new Two(options).appendTo(box);
var c= two.makeCircle(200,200,100);
var r = two.makeRectangle(600,200,200,200)
two.update();//跟新DOM tree
</script>
</body>
</html>