原 九、客户端检测

function getWindowWidth(){
    if ( document.all ){  //假设是IE，但实际上能支持document.all的浏览器不止IE，比如说Opera
        return document.documentElement.clientWidth;  //错误的用法！
    } else {
        return window.innerWidth;
    }
}

fucntion isHostMethod( object, property ){
   var t = typeof object[property];
   return t == 'fucntion' || (!!(t == 'object' && object[property])) || t == 'unknown';
}

// 调用
result = isHostMethod(xhr, "open");  //true
result = isHostMethod(xhr, "foo");  //false

var hasEnumShadowsQuirk = function(){
    var o = { toString: function(){} };
    var count = 0;
    for( var prop in o){
        if( prop == "toString" ){
            count++;
        }
    }
    
    return (count > 1);
}

(function() {
	window.client = {};
	
	//呈现引擎
	var engine = {
		//呈现引擎
		ie: 0,
		gecko: 0,
		webkit: 0,
		khtml: 0,
		opera: 0,
		//具体版本号
		ver: null
	};
	var browser = {
		//浏览器
		ie: 0,
		edge: 0,
		firefox: 0,
		safari: 0,
		konq: 0,
		opera: 0,
		chrome: 0,
		//具体版本号
		ver: null
	};
	//平台、设备和操作系统
	var system = {
		win: false,
		mac: false,
		unix: 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, //任天堂
		ps: false //Playstation3
	};
	
	var ua = window.navigator.userAgent;

	//检测Presto内核的Opera浏览器
	if(window.opera) {
		engine.ver = browser.ver = window.opera.version();
		engine.opera = browser.opera = parseFloat(engine.ver);
	}
	//检测WebKit 用代理字符串中的"AppleWebKit"进行检测
	else if(/AppleWebKit\/(\S+)/.test(ua)) {
		engine.ver = RegExp["$1"];
		engine.webkit = parseFloat(engine.ver);
		//确定Microsoft Edge
		if(/Edge\/(\S+)/.test(ua)) {
			browser.ver = RegExp["$1"];
			browser.edge = parseFloat(browser.ver);
		}
		//确定WebKit内核Opera
		else if(/OPR\/(\S+)/.test(ua)) {
			browser.ver = RegExp["$1"];
			browser.opera = parseFloat(browser.ver);
		}
		//确定Chrome
		else if(/Chrome\/(\S+)/.test(ua)) {
			browser.ver = RegExp["$1"];
			browser.chrome = parseFloat(browser.ver);
		}
		//确定Safari
		else if(/Version\/(\S+)/.test(ua)) {
			browser.ver = RegExp["$1"];
			browser.safari = parseFloat(browser.ver);
		} else {
			//近似的确定版本号
			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.ver = browser.safari = safariVersion;
		}
	}
	//检测KHTML 用于Konqueror3.1及更早版本中不包含KHTML的版本，故而就要使用Konqueror的版本来代替
	else if(/KHTML\/(\S+)/.test(ua) || /Konqueror\/(\S+)/.test(ua)) {
		engine.ver = browser.ver = RegExp["$1"];
		engine.khtml = browser.konq = parseFloat(engine.ver);
		s
	}
	//检测Gecko 其版本号在字符串"rv:"的后面
	else if(/rv:([^\)]+)\) Gecko\/\d{8}/.test(ua)) {
		engine.ver = RegExp["$1"];
		engine.gecko = parseFloat(engine.ver);
		//确定Firefox
		if(/Firefox\/(\S+)/.test(ua)) {
			browser.ver = RegExp["$1"];
			browser.firefox = parseFloat(browser.ver);
		}
	}
	//检测IE
	else if(/MSIE ([^;]+)/.test(ua) || /rv:([^\)]+)\) like Gecko/.test(ua)) {
		engine.ver = browser.ver = RegExp["$1"];
		engine.ie = browser.ie = parseFloat(engine.ver);
	}
	//获取平台或者操作系统信息,可能的值：win32、win64、MacPPC、MacIntel、Xll、Linux i686
	var p = window.navigator.platform;
	//检测平台
	system.win = p.indexOf("Win") == 0;
	system.mac = p.indexOf("Mac") == 0;
	system.unix = (p == "Xll'") || (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 "7":
						system.win = "7";
						break;
					case "8":
						system.win = "8";
						break;
					case "8.1":
						system.win = "8.1";
						break;
					case "10.0":
						system.win = "10.0";
						break;
					default:
						system.win = "NT";
						break;
				}
			}
		}
	}
	//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;
	//window 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
		}
	}
	//检测安卓版本
	if(/Android (\d+.\d+)/.test(ua)) {
		system.android = parseFloat(RegExp["$1"]);
	}
	//检测游戏系统
	system.wii = ua.indexOf("wii") > -1;
	system.ps = /playstation/i.test(ua);
	
	window.iClient.engine = engine;
	window.iClient.browser = browser;
	window.iClient.system = system;
})();