JS自动识别浏览器

var userAgent = navigator.userAgent,
rMsie = /(msie\s|trident.*rv:)([\w.]+)/,        //IE
rFirefox = /(firefox)\/([\w.]+)/,           //Firefox
rOpera = /(opera).+version\/([\w.]+)/,      //Opera
rChrome = /(chrome)\/([\w.]+)/,             //Chrome
rMicromessenger = /(micromessenger)\/([\w.]+)/,     //微信
rSafari = /version\/([\w.]+).*(safari)/;
var browser;
var version;
function uaMatch(ua) {
var match = rMsie.exec(ua);
if (match != null) {
return { browser : "IE", version : match[2] || "0" };
}
var match = rFirefox.exec(ua);
if (match != null) {
return { browser : match[1] || "", version : match[2] || "0" };
}
var match = rOpera.exec(ua);
if (match != null) {
return { browser : match[1] || "", version : match[2] || "0" };
}
var match = rChrome.exec(ua);
if (match != null) {
return { browser : match[1] || "", version : match[2] || "0" };
}
var match = rMicromessenger.exec(ua);
if (match != null) {
return { browser : match[1] || "", version : match[2] || "0" };
}
var match = rSafari.exec(ua);
if (match != null) {
return { browser : match[2] || "", version : match[1] || "0" };
}
if (match != null) {
return { browser : "", version : "0" };
}
}
var browserMatch = uaMatch(userAgent.toLowerCase());
if (browserMatch.browser)
{
browser = browserMatch.browser;
version = browserMatch.version;
}
alert(browser+version);