js 浏览器版本及版本号判断函数2009年

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> 
<title>js判断浏览器版本及版本号</title> 
<meta name="keywords" content="js 浏览器 版本 ie7 ie8 firefox2 firefox3" /> 
<meta name="description" content="js判断浏览器版本及版本号，本代码支持最新的ie7，ie8，firefox2，firefox3的判断" /> 
<meta name="author" content="" /> 
<meta name="Copyright" content="Copyright (c) 2008-2010 " /> 
<script>

window["MzBrowser"]={};(function() 
{ 
if(MzBrowser.platform) return; 
var ua = window.navigator.userAgent; 
MzBrowser.platform = window.navigator.platform;

MzBrowser.firefox = ua.indexOf("Firefox")>0; 
MzBrowser.opera = typeof(window.opera)=="object"; 
MzBrowser.ie = !MzBrowser.opera && ua.indexOf("MSIE")>0; 
MzBrowser.mozilla = window.navigator.product == "Gecko"; 
MzBrowser.netscape= window.navigator.vendor=="Netscape"; 
MzBrowser.safari= ua.indexOf("Safari")>-1;

if(MzBrowser.firefox) var re = /Firefox(\s|\/)(\d+(\.\d+)?)/; 
else if(MzBrowser.ie) var re = /MSIE( )(\d+(\.\d+)?)/; 
else if(MzBrowser.opera) var re = /Opera(\s|\/)(\d+(\.\d+)?)/; 
else if(MzBrowser.netscape) var re = /Netscape(\s|\/)(\d+(\.\d+)?)/; 
else if(MzBrowser.safari) var re = /Version(\/)(\d+(\.\d+)?)/; 
else if(MzBrowser.mozilla) var re = /rv(\:)(\d+(\.\d+)?)/;

if("undefined"!=typeof(re)&&re.test(ua)) 
MzBrowser.version = parseFloat(RegExp.$2); 
})();

function aa() 
{ 
if(MzBrowser.ie) 
{ 
alert('ie'); 
} 
if(MzBrowser.firefox) 
{ 
alert('firefox'); 
} 
alert(MzBrowser.version); 
} 
aa();

</script> 
</head>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]