檢測瀏覽器，注意瀏覽器判斷順序，主要是基於userAgent做判斷。
//檢測瀏覽器var client = function(){var engine = {ie:0,gecko:0,webkit:0,khtml:0,opera:0,ver:null};var browser = {//瀏覽器ie: 0,firefox: 0,safari: 0,konq: 0,opera: 0,chrome: 0,ver:null};var ua = navigator.userAgent;//瀏覽器檢測有順序if(window.opera){//opera偽裝，所以優先檢測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);//確定是Chrome 還是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 {//近似地確定版本號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);//確定是不是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};}();//調用if (client.engine.webkit) { //if it's WebKit if (client.browser.chrome){ //執行針對Chrome 的代碼} else if (client.browser.safari){ //執行針對Safari 的代碼} } else if (client.engine.gecko){ if (client.browser.firefox){ //執行針對Firefox 的代碼} else { //執行針對其他Gecko 瀏覽器的代碼} }