JavaScript监听浏览器窗口关闭事件的多种实现方案

<script type="text/javascript">
window.onbeforeunload=onclose;
function onclose()
{
if(event.clientX>document.body.clientWidth&&event.clientY<0||event.altKey)
{
return "您要离开吗？";
}
}
</script>

<script type="text/javascript">
  window.onbeforeunload = onbeforeunload_handler;
  window.onunload = onunload_handler;
  function onbeforeunload_handler(){
    var warning="确认退出?";
    return warning;
  }
  function onunload_handler(){
    var warning="谢谢光临";
    alert(warning);
  }
</script>

<script type="text/javascript">
window.onbeforeunload=onclose;
function onclose()
{
return "您确定退出吗？";
}
</script>

<script language="javascript">
var MSG_UNLOAD="如果你此时离开档案系统，所做操作信息将全部丢失，是否离开?";
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>

<script type="text/javascript">
window.onbeforeunload=onclose;
function onclose()
{
var warnning = '<fmt:message key="systemMessage.exitWarning" />';
var beforeExit='<fmt:message key="systemMessage.beforeExitWarning" />';
 if(event.clientY<0 && event.clientX>document.body.clientWidth-20 || event.clientY<0 && event.clientX<20 ||
event.altKey || event.ctrlKey || event.clientY>document.body.clientHeight){
alert(beforeExit);
return warnning;
}
}
</script>

<script type="text/javascript">
    var Sys = {};
    var ua = navigator.userAgent.toLowerCase();
    if (window.ActiveXObject)
      Sys.ie = ua.match(/msie ([\d.]+)/)[1]
    else if (document.getBoxObjectFor)
      Sys.firefox = ua.match(/firefox\/([\d.]+)/)[1]
    else if (window.MessageEvent && !document.getBoxObjectFor)
      Sys.chrome = ua.match(/chrome\/([\d.]+)/)[1]
    else if (window.opera)
      Sys.opera = ua.match(/opera.([\d.]+)/)[1]
    else if (window.openDatabase)
      Sys.safari = ua.match(/version\/([\d.]+)/)[1];
    //以下进行测试
    if(Sys.ie) document.write('IE: '+Sys.ie);
    if(Sys.firefox) document.write('Firefox: '+Sys.firefox);
    if(Sys.chrome) document.write('Chrome: '+Sys.chrome);
    if(Sys.opera) document.write('Opera: '+Sys.opera);
    if(Sys.safari) document.write('Safari: '+Sys.safari);
</script>

<script type="text/javascript">
window.onbeforeunload=onclose;
function onclose()
{
var Sys = {};
var warnning = '<fmt:message key="systemMessage.exitWarning" />';
var ua = navigator.userAgent.toLowerCase();
if (window.ActiveXObject)
  Sys.ie = ua.match(/msie ([\d.]+)/)[1]
else if (document.getBoxObjectFor)
  Sys.firefox = ua.match(/firefox\/([\d.]+)/)[1]
if(Sys.ie) {//for IE
if(event.clientX>document.body.clientWidth&&event.clientY<0||event.altKey)
{
window.event.returnValue = warnning ;
}
}
if(Sys.firefox) //for FF
return warnning;
}
</script>

<script type="text/javascript">
if(-[1,]){
   alert("这不是IE浏览器！");
}else{
   alert("这是IE浏览器！");
}
</script>