js检测浏览器代理信息，包括浏览器类型、系统类型，浏览器引擎类型、移动设备类型和游戏系统

以下代码用于检测完整的用户代理字符串，包括检测呈现引擎、平台、Windows 操作系统、移动设备和游戏系统。

用法示例：检测是不是ie浏览器的方法如下：
if(client.browser.ie > 0){       
   console.log('Is IE.');
}

代码如下：
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
  };
}();