判断浏览器版本号JS方法

var Sys = {}; var ua = navigator.userAgent.toLowerCase(); if (window.ActiveXObject) Sys.ie = ua.match(/msie ([/d.]+)/)[1] else if (document.getBoxObjectFor) Sys.firefox = ua.match(/firefox//([/d.]+)/)[1] else if (window.MessageEvent && !document.getBoxObjectFor) Sys.chrome = ua.match(/chrome//([/d.]+)/)[1] else if (window.opera) Sys.opera = ua.match(/opera.([/d.]+)/)[1] else if (window.openDatabase) Sys.safari = ua.match(/version//([/d.]+)/)[1];