<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script type="text/javascript">
var main = document.body;
function cr(ulr,text)
{
var a=document.createElement("a");
a.href=ulr;
main.appendChild(a);
a.innerHTML=text;
a.style.color="red";
a.style.textDecoration="none";
}
cr("http://www.imooc.com","慕课网");
</script>
</body>
</html>
cr是啥