帮忙看下代码哪里错了,单击button没有反应
<html>
<head>
<meta charset="utf-8">
<title>打开新网页</title>
<script type="text/javascript">
function wopen(){
var mess =confirm("确认要打开新窗口吗");
if(mess==true){
var _url = prompt("请输入要的开的网址","http://www.immc.com");
window.open(_url,"_blank");}
else
{alert("再见")}
}
</script>
</head>
<body>
<input type="button" value="新窗口打开网站" onClick="wopen()"/>
</body>
</html>