JavaScript客户端检测

(function(window){
 	var realwall = {
		detection : (function(){
			var ua = navigator.userAgent.toLowerCase();
			alert(ua);
			var pattern = {
				ie : /^(?!.*?opera)(.*?)msie(.*?)$/,
				opera : /opera/,
				safari : /version.*satari/,
				chrome : /chrome/,
				firefox : /^(?!.*?webkit)(.*?)gecko(.*?)$/
			}
			var IEVersion = function(ua){
				var begin = ua.indexOf('msie');
				if(begin < 0){
					return 0;
				}else{
					return parseFloat(ua.substring(begin + 5, ua.indexOf(';', begin)));
				}
			};
			var IE67 = function(ua){
				var ieVer = IEVersion(ua);
				if(ieVer > 5 && ieVer < 8){
					return true;
				}else{
					return false;
				}
			};
			var sysInfo = function(ua){
				var begin,
					win = ua.indexOf('Win'),
					unix = ua.indexOf('X11'),
					mac = ua.indexOf('Mac'),
					linux = ua.indexOf('Linux');
				if(win > -1){
					begin = win;
				}else if(unix > -1){
					begin = unix;
				}else if(mac > -1){
					begin = mac;
				}else if(linux > -1){
					begin = linux;
				}else{
					return '';
				}
				return ua.substring(begin, ua.indexOf(';', begin));
			};
			var detection = {
				isIE : pattern.ie.test(ua),
				isOpera : pattern.opera.test(ua),
				isSafari : pattern.safari.test(ua),
				isChrome : pattern.chrome.test(ua),
				isFirefox : pattern.firefox.test(ua),
				getIEVersion : IEVersion(ua),
				isIE67 : IE67(ua),
				getSysInfo : sysInfo(navigator.userAgent)
			}
			return detection;
		})()
	};
	window.realwall = realwall;
 })(window);


alert(realwall.detection.getSysInfo);