var ua = navigator.userAgent;
if (window.opera){
engine.ver = window.opera.version();
engine.opera = parseFloat(engine.ver);
} else if (/AppleWebKit\/(\S+)/.test(ua)){
engine.ver = RegExp["$1"];
engine.webkit = parseFloat(engine.ver);
} else if (/KHTML\/(\S+)/.test(ua)) {
engine.ver = RegExp["$1"];
engine.khtml = parseFloat(engine.ver);
} else if (/rv:([^\)]+)\) Gecko\/\d{8}/.test(ua)){
engine.ver = RegExp["$1"];
engine.gecko = parseFloat(engine.ver);
} else if (/MSIE ([^;]+)/.test(ua)){
engine.ver = RegExp["$1"];
engine.ie = parseFloat(engine.ver);
}

浏览器检测代码