大神，调用后页面没结果，即使用慕课提供的代码也同样结果？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
</head>
<body>
<script type="text/javascript">
var main = document.body;
//创建链接
function createa(url,text)
{
var a1=document.createElement('a');
a1.href=url;
a1.innerHTML=text;
a1.style.color='red';
body.appendChild(a1);
}
// 调用函数创建链接
setTimeout("createa('http://www.imooc.com/','慕课网')",0);
</script>
</body>
</html>
