捕捉浏览器的刷新与关闭 兼容ie、ff

<script language="javascript">var MSG_UNLOAD="确定离开？";var UnloadConfirm = {};//启用监听浏览器刷新、关闭的方法UnloadConfirm.set = function(confirm_msg){    window.onbeforeunload = function(event){        event = event || window.event;        event.returnValue = confirm_msg;    }}//关闭监听浏览器刷新、关闭的方法UnloadConfirm.clear = function(){    window.onbeforeunload = function(){};}UnloadConfirm.set(MSG_UNLOAD);</script>