解析javascript 浏覽器關閉事件

　　代碼如下:
<script type="text/javascript"> 
    windowonbeforeunload = onbeforeunload_handler; 
    windowonunload = onunload_handler; 
    function onbeforeunload_handler(){ 
        var warning="確認退出?";         
        return warning;   //可以換成alert等具體操作
    } 

    function onunload_handler(){ 
        var warning="謝謝光臨"; 
        alert(warning);   //關閉後執行
    } 
</script>

From:http://tw.wingwit.com/Article/program/Java/JSP/201311/19935.html