js检测各个浏览器版本，包括IE11

<script type="text/javascript">
    var userAgent = navigator.userAgent,
            rMsie = /(msie\s|trident.*rv:)([\w.]+)/,
            rFirefox = /(firefox)\/([\w.]+)/,
            rOpera = /(opera).+version\/([\w.]+)/,
            rChrome = /(chrome)\/([\w.]+)/,
            rSafari = /version\/([\w.]+).*(safari)/;
    var browser;
    var version;
    var ua = userAgent.toLowerCase();
    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 = 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;
    }
    document.write(browser+version);
</script>