JS check browser type and version

First obtain the lowercase information of the userAgent attribute of the Navigator object, and then judge the assignment based on the regular expression.

var Sys = {};  
var ua = navigator.userAgent.toLowerCase();  
var s;  
var scan;  
(s = ua.match(/msie ([\d.]+)/)) ? Sys.ie = s[1] : (s = ua  
        .match(/firefox\/([\d.]+)/)) ? Sys.firefox = s[1] : (s = ua  
        .match(/chrome\/([\d.]+)/)) ? Sys.chrome = s[1] : (s = ua  
        .match(/opera.([\d.]+)/)) ? Sys.opera = s[1] : (s = ua  
        .match(/version\/([\d.]+).*safari/)) ? Sys.safari = s[1] : 0;  
   
//进行测试  
if (Sys.ie) {  
    scan = "您使用的ie内核" + Sys.ie + "浏览器";  
}  
if (Sys.firefox) {  
    scan = "您使用的是firefox内核" + Sys.firefox + "浏览器";  
}  
if (Sys.chrome) {  
    scan = "您使用的是chrome内核" + Sys.chrome + "浏览器";  
}  
if (Sys.opera) {  
    scan = "您使用的是opera内核" + Sys.opera + "浏览器";  
}  
if (Sys.safari) {  
    scan = "您使用的是safari内核" + Sys.safari + "浏览器";  
}  
alert(scan)