2-7，点了打开 ‘新窗口打开网站’ 按钮，发现一点用都没有，求大神看看我错在哪？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>confirm</title>
<script type="text/javascript">
function Wopen()
{
var a;
var b=confirm("是否打开");
if(b==true)
{
var a =prompt("请输入:http://www.imooc.com/");
if(a==http://www.imooc.com/)
{
window.open('http://www.imooc.com','width=400','heith=500','menubar=no','toolbar=no')
}
}
}
</script>
</head>
<body>
<input name="button" type="button" onClick="Wopen()" value="新窗口打开网站" />
</body>
</html>
