<html>
<head>
<script language="javascript">
window.onbeforeunload=function()
{
return "您确定关闭该窗口么？";
}
</script>
</head>
<body>
</body>
</html>
或者
<html>
<head>
<script>
function ClosePage()
{
return "你确定要离开当前页面吗？";
}
</script>
</head>
<body onbeforeunload="return ClosePage()">
</body>
</html>