javascript判定不同瀏覽器

除了另無它法，肯定不使用navigator.userAgent來判定瀏覽器。因為在第一次瀏覽器大戰初期，Netscape占絕對統計地位，大 部分人們不願意相容其他瀏覽器，並通過檢測其UA讓他們的網站只允許Netscape訪問，這就逼使其他瀏覽器（包括IE）修改自己的UA偽裝成 Netscape來通過那些自以為是的指令碼，於是出現每個人都聲稱自己是別人的局面，即使最新的IE9的UA也是:

 

 //Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; Trident/5.0)

//2010 4 16日更新        ie = !+"\v1" ;        ie = !-[1,];//IE9預覽版中失效        ie ='\v'=='v' ;        ie = !!document.recalc        ie = !!window.VBArray        ie = !!window.ActiveXObject        ie = 0//@cc_on+1;        ie = !!window.createPopup;        ie = /*@cc_on!@*/!1;        ie = document.expando;//document.all在opera firefox的古老版本也存在        ie = /\w/.test('\u0130') //由群裡的abcd友情提供                ie6 = !"1"[0] //利用IE6或IE5的字串不能使用數組下標的特徵        ie8 = !!window.XDomainRequest;        ie9 =  document.documentMode && document.documentMode === 9;        //自創，基於條件編譯的嗅探指令碼，IE會返回其JS引擎的版本號碼，非IE返回0        var ieVersion = eval("''+/*@cc_on"+" @_jscript_version@*/-0")*1        ie9 = ieVersion === 5.9        ie8 = ieVersion === 5.8        ie7 = ieVersion === 5.7        ie6 = ieVersion === 5.6        ie5 = ieVersion === 5.5        //https://developer.mozilla.org/En/Windows_Media_in_Netscape        netscape = !!window.GeckoActiveXObject         gecko  = !!window.netscape //包括firefox        firefox = !!window.Components        firefox = !!window.updateCommands        safari = !!(navigator.vendor && navigator.vendor.match(/Apple/))        safari = window.openDatabase && !window.chrome;        chrome= !!(window.chrome && window.google)        opera=!!window.opera ;        //傲遊2 3        maxthon = /maxthon/i.test(navigator.userAgent)        //360安全瀏覽器        is360se = /360se/i.test(navigator.userAgent)//2010.6.4       setTimeout(function(){//FF的setTimeout總是有一個額餘的參數0          var isFF = !!arguments.length;          alert(isFF)        }, 0); //判定IE版本2010.10.1      ie = (function(undefined){        var v = 3, div = document.createElement('div');        while (        div.innerHTML = '<!--[if gt IE '+(++v)+']><i></i><![endif]-->',        div.getElementsByTagName('i')[0]);        return v> 4 ? v : undefined;      }()); //判定IE版本 2011.2.24       ie = (function() {          var v = 3, div = document.createElement('div'), a = div.all || [];          while (div.innerHTML = '<!--[if gt IE '+(++v)+']><br><![endif]-->', a[0]);          return v > 4 ? v : !v;        }());    //手機的相關判定 2011.9.21 isIPhone = /iPhone/i.test(navigator.userAgent); isIPhone4 = window.devicePixelRatio >= 2//在網頁中，pixel與point比值稱為device-pixel-ratio，普通裝置都是1，iPhone 4是2，有些Android機型是1.5//http://blog.webcreativepark.net/2011/01/25-173502.html isIPad = /iPad/i.test(navigator.userAgent); isAndroid = /android/i.test(navigator.userAgent); isIOS = isIPhone  || isIPad ;     

isMobile = isIOS || isAndroid ;