为什么这样做没有输出？
<!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 newUrl=document.createElement("a");
newUrl.setAttribute("href",url);
newUrl.setAttribute("value",text);
newUrl.style.color="red";
main.appendChild(newUrl);
}
// 调用函数创建链接
createa("http://www.imooc.com","慕课网");
</script>
</body>
</html>
