【javascript】浏览器用户代理检测脚本实现

var client = function(){

	// 呈现引擎
	var engine = {
		ie: 0,
		gecko: 0,
		webkit: 0,
		khtml: 0,
		opera: 0,
		// 完整的版本号
		ver: null
	};

	// 浏览器
	var browser = {
		// 主要浏览器
		ie: 0,
        firefox: 0,
        safari: 0,
        konq: 0,
        opera: 0,
        chrome: 0,
		// 具体的版本号
		ver: null
	};

	// 平台、设备和操作系统
	var system = {
		win: false,
		mac: false,
		x11: false,

		// 移动设备
		iphone: false,
        ipod: false,
        ipad: false,
        ios: false,
        android: false,
        nokiaN: false,
        winMobile: false,

		// 游戏系统
		wii: false,
		ps: false
	};

	// 检测呈现引擎和浏览器
	 var ua = navigator.userAgent;    
    if (window.opera){
        engine.ver = browser.ver = window.opera.version();
        engine.opera = browser.opera = parseFloat(engine.ver);
    } 
    else if (/AppleWebKit\/(\S+)/.test(ua)){
        engine.ver = RegExp["$1"];
        engine.webkit = parseFloat(engine.ver);

		// 确定是Chroeme还是Safari
		 if (/Chrome\/(\S+)/.test(ua)){
            browser.ver = RegExp["$1"];
            browser.chrome = parseFloat(browser.ver);
        } else if (/Version\/(\S+)/.test(ua)){
            browser.ver = RegExp["$1"];
            browser.safari = parseFloat(browser.ver);
        } 
        else {
			// 近似地确定版本号
			 var safariVersion = 1;
            if (engine.webkit < 100){
                safariVersion = 1;
            } else if (engine.webkit < 312){
                safariVersion = 1.2;
            } else if (engine.webkit < 412){
                safariVersion = 1.3;
            } else {
                safariVersion = 2;
            }   
            
            browser.safari = browser.ver = safariVersion;        
        }
    } 
    else if (/KHTML\/(\S+)/.test(ua) || /Konqueror\/([^;]+)/.test(ua)){
        engine.ver = browser.ver = RegExp["$1"];
        engine.khtml = browser.konq = parseFloat(engine.ver);
    } 
    else if (/rv:([^\)]+)\) Gecko\/\d{8}/.test(ua)){   
        engine.ver = RegExp["$1"];
        engine.gecko = parseFloat(engine.ver);
       
		// 确定是不是Firefox
		 if (/Firefox\/(\S+)/.test(ua)){
            browser.ver = RegExp["$1"];
            browser.firefox = parseFloat(browser.ver);
        }
    } 
    else if (/MSIE ([^;]+)/.test(ua)){    
        engine.ver = browser.ver = RegExp["$1"];
        engine.ie = browser.ie = parseFloat(engine.ver);
    }

	// 检测浏览器
	browser.ie = engine.ie;
    browser.opera = engine.opera;

	// 检测平台
	var p = navigator.platform;
	system.win = p.indexOf("Win") == 0;
	system.mac = p.indexOf("Mac") == 0;
	system.x11 = (p == "x11") || (p.indexOf("Linux") == 0);

	// 检测windows操作系统
	if(system.win){
		if(/win(?:dows )?([^do]{2})\s?(\d+\.\d+)?/.test(ua)){
			if(RegExp["$1"] == "NT"){
				switch(RegExp["$2"]){
					case "5.0":
						system.win = "2000";
						break;
					case "5.1":
						system.win = "XP";
						break;
					case "6.0":
						system.win = "Vista";
						break;
					case "6.1":
						system.win = "7";
						break;
					default:
						system.win = "NT";
						break;
				}
			} 
			else if(RegExp["$1"] == "9x"){
				system.win = "ME";
			}
			else{
				system.win = RegExp["$1"];
			}
		}
	}

	// 移动设备
	system.iphone = ua.indexOf("iPhone") > -1;
	system.ipod = ua.indexOf("iPod") > -1;
	system.ipad = ua.indexOf("iPad") >-1;
	system.nokiaN = ua.indexOf("NokiaN") > -1;

	// windows mobile
	if(system.win == "CE"){
		system.winMobile = system.win;
	}
	else if(system.win == "Ph" ){
		if(/Windows Phone OS (\d+.\d+)/.test(ua)){
			system.win = "Phone";
			system.winMobile = parseFloat(RegExp["$1"]);
		}
	}

	// 检测IOS版本
	if(system.mac && ua.indexOf("Mobile")> -1){
		if(/CPU (?:Phone )?OS (\d+_\d+)/.test(ua)){
			system.ios = parseFloat(RegExp.$1.replace("_","."));
		}
		else{
			system.ios = 2;
			// 不能真正检测出来，所以只能猜测
		}
	}

	// 检测Android版本
	if(/Android (\d+\.\d+)/.test(ua)){
		system.android = parseFloat(RegExp.$1);
	}

	// 游戏系统
	system.wii = ua.indexOf("Wii") > -1;
	system.ps = /playstation/i.test(ua);

	// 返回这些对象
	return {
        engine:     engine,
        browser:    browser,
        system:     system        
    };

  	// console.log(engine);
   //  console.log(browser);
   //  console.log(system);
}();