检测当前浏览器及版本

废话不多说，直接上代码：
 1 detectBrowser() {
 2       var Sys = {};
 3       var ua = navigator.userAgent.toLowerCase();
 4       var s;
 5       (s = ua.match(/firefox/([d.]+)/)) ? Sys.firefox = s[1] :
 6         (s = ua.match(/chrome/([d.]+)/)) ? Sys.chrome = s[1] :
 7           (s = ua.match(/opera.([d.]+)/)) ? Sys.opera = s[1] :
 8             (s = ua.match(/rv:([d.]+)/)) ? Sys.ie = s[1] :
 9               (s = ua.match(/msie ([d.]+)/)) ? Sys.ie = s[1] :
10                 (s = ua.match(/version/([d.]+).*safari/)) ? Sys.safari = s[1] : 0;
11 
12       var browser = "Unknown";
13       if (Sys.ie) { browser = "IE"; }
14       if (Sys.firefox) { browser = "Firefox"; }
15       if (Sys.chrome) { browser = "Chrome"; }
16       if (Sys.opera) { browser = "Opera"; }
17       if (Sys.safari) { browser = "Safari"; }
18 
19       return browser;
20     }