求助!想问下我的代码问题出在哪?打不开
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script type="text/javascript">
function openWindow()
{
var opentag=confirm("是否在新窗口打开网站?");
if (opentag==true)
{
var webadress=prompt("请输入网址"," http://www.imooc.com/");
if(webadress!=null)
{
window.open(webadress,'_blank','width=400,height=500,menubar=no,toolbar=no');
}
else
{alert("结束");}
};
else
{alert("结束");}
}
</script>
</head>
<body>
<input type="button" value="新窗口打开网站" onclick="openWindow()"/ >
</body>
</html>