<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>useragent.html</title>
	
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">   
	
  </head>
  <script type="text/javascript">
  		//获是userAgent信息，里面表示浏览器的相关信息
  		//navigator.appVersion获得版本号的信息
  		var sUserAgent = navigator.userAgent;
		
		
		//为MinMoz准备的,比较版本号,因为它的版本号有与从不同
		
		function compareVersions(sVersion1, sVersion2) {
		
		    var aVersion1 = sVersion1.split(".");
		    var aVersion2 = sVersion2.split(".");
		    
		    if (aVersion1.length > aVersion2.length) {
		        for (var i=0; i < aVersion1.length - aVersion2.length; i++) {
		        	//差的位数就放入0
		            aVersion2.push("0");
		        }
		    } else if (aVersion1.length < aVersion2.length) {
		        for (var i=0; i < aVersion2.length - aVersion1.length; i++) {
		            aVersion1.push("0");
		        }    
		    }
		    
		    for (var i=0; i < aVersion1.length; i++) {
		 		//比如版本号的大小
		 		
		        if (aVersion1[i] < aVersion2[i]) {
		            return -1;
		        } else if (aVersion1[i] > aVersion2[i]) {
		            return 1;
		        }    
		    }		    
		    return 0;		
		}
		
		//查看是不是IE的浏览器,同时要满足以下两个要求,但没有考虑到Opera
		
  		var isIE = sUserAgent.indexOf("compatible") > -1 && sUserAgent.indexOf("MSIE") > -1; 
  		          
		//下面就判断是那个版本的IE,还没有加入IE7和IE8我这没有,不知道版本号....那位能帮我加一下	           
		var isMinIE4 = isMinIE5 = isMinIE5_5 = isMinIE6 = false;
		
		if (isIE) {
		    var reIE = new RegExp("MSIE (\\d+\\.\\d+);");//用正则表示式去获得版本号
		    reIE.test(sUserAgent);
		    var fIEVersion = parseFloat(RegExp["$1"]);
		
		    isMinIE4 = fIEVersion >= 4;		//true or false
		    isMinIE5 = fIEVersion >= 5;
		    isMinIE5_5 = fIEVersion >= 5.5;
		    isMinIE6 = fIEVersion >= 6.0;
		}
		
		//查看是不是MinMoz的浏览器
		
  		var isMoz = sUserAgent.indexOf("Gecko") > -1;
		//下面就判断是那个版本的FF
		
		var isMinMoz1 = sMinMoz1_4 = isMinMoz1_5 = false;

		if (isMoz) {
		    var reMoz = new RegExp("rv:(\\d+\\.\\d+(?:\\.\\d+)?)");
		    reMoz.test(sUserAgent);
		    isMinMoz1 = compareVersions(RegExp["$1"], "1.0") >= 0;
		    isMinMoz1_4 = compareVersions(RegExp["$1"], "1.4") >= 0;
		    isMinMoz1_5 = compareVersions(RegExp["$1"], "1.5") >= 0;
		}
  		//查看操作系统
  		var isWin = (navigator.platform == "Win32") || (navigator.platform == "Windows");
		var isMac = (navigator.platform == "Mac68K") || (navigator.platform == "MacPPC") 
            || (navigator.platform == "Macintosh");

		var isUnix = (navigator.platform == "X11") && !isWin && !isMac;
		//先全部设为false
		var isWin95 = isWin98 = isWinNT4 = isWin2K = isWinME = isWinXP = false;
		var isMac68K = isMacPPC = false;
		var isSunOS = isMinSunOS4 = isMinSunOS5 = isMinSunOS5_5 = false;
		
		if (isWin) {
		    isWin95 = sUserAgent.indexOf("Win95") > -1 
		              || sUserAgent.indexOf("Windows 95") > -1;
		    isWin98 = sUserAgent.indexOf("Win98") > -1 
		              || sUserAgent.indexOf("Windows 98") > -1;
		    isWinME = sUserAgent.indexOf("Win 9x 4.90") > -1 
		              || sUserAgent.indexOf("Windows ME") > -1;
		    isWin2K = sUserAgent.indexOf("Windows NT 5.0") > -1 
		              || sUserAgent.indexOf("Windows 2000") > -1;
		    isWinXP = sUserAgent.indexOf("Windows NT 5.1") > -1 
		              || sUserAgent.indexOf("Windows XP") > -1;
		    isWinNT4 = sUserAgent.indexOf("WinNT") > -1 
		              || sUserAgent.indexOf("Windows NT") > -1 
		              || sUserAgent.indexOf("WinNT4.0") > -1 
		              || sUserAgent.indexOf("Windows NT 4.0") > -1 
		              && (!isWinME && !isWin2K && !isWinXP);
		} 
		//没玩过苹果机....
		if (isMac) {
		    isMac68K = sUserAgent.indexOf("Mac_68000") > -1 
		               || sUserAgent.indexOf("68K") > -1;
		    isMacPPC = sUserAgent.indexOf("Mac_PowerPC") > -1 
		               || sUserAgent.indexOf("PPC") > -1;  
		}

		if (isUnix) {
		    isSunOS = sUserAgent.indexOf("SunOS") > -1;
		
		    if (isSunOS) {
		        var reSunOS = new RegExp("SunOS (\\d+\\.\\d+(?:\\.\\d+)?)");
		        reSunOS.test(sUserAgent);
		        isMinSunOS4 = compareVersions(RegExp["$1"], "4.0") >= 0;
		        isMinSunOS5 = compareVersions(RegExp["$1"], "5.0") >= 0;
		        isMinSunOS5_5 = compareVersions(RegExp["$1"], "5.5") >= 0;
		    }
		}
  		
  		window.onload = function(){
  			//这是我的环境
		  	if(isMinIE6){
				 alert("当前浏览器是IE"); 	
			}
			if(isWinXP){
				 alert("当前系统是Windows XP"); 	
			}			
  		}
  	
  </script>
  <body>
   
  </body>
</html>