js 检测浏览器

//检测呈现引擎、平台、Windows操作系统、移动设备和游戏系统。

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 Chrome 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 (?:iPhone )?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
    };
}();