我这个哪里出现问题了
<!DOCTYPE html>
<html>
<head>
<title> new document </title>
<meta http-equiv="Content-Type" content="text/html; charset=gbk"/>
<script type="text/javascript">
function openWindow()
{var open=confirm("是否新建网页?");
if(open==true)
{var url=prompt("通过输入对话框","确定打开的网址,默认为 http://www.imooc.com/")
if(url!=null)
{window.open(url,"_blank",'width=400,height=400,menubar=no,toolbar=no');
}
else
{alert("byebye");}
else
{alert("拜拜");}
}
</script>
</head>
<body>
<input type="button" value="新窗口打开网站" onclick="openWindow()" />
</body>
</html>