检测浏览器，注意浏览器判断顺序，主要是基于userAgent做判断。
//检测浏览器var client = function(){var engine = {ie:0,gecko:0,webkit:0,khtml:0,opera:0,ver:null};var browser = {//浏览器ie: 0,firefox: 0,safari: 0,konq: 0,opera: 0,chrome: 0,ver:null};var ua = navigator.userAgent;//浏览器检测有顺序if(window.opera){//opera伪装，所以优先检测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 Safariif (/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 Firefoxif (/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);}return {engine:engine,browser: browser};}();//调用if (client.engine.webkit) { //if it's WebKit if (client.browser.chrome){ //执行针对 Chrome 的代码 } else if (client.browser.safari){ //执行针对 Safari 的代码 } } else if (client.engine.gecko){ if (client.browser.firefox){ //执行针对 Firefox 的代码 } else { //执行针对其他 Gecko 浏览器的代码 } }