A Browser detector. Because sometimes, there is no other way, and not even good modern browsers always provide good feature detection mechanisms.

/*!
 * Bowser - a browser detector
 * https://github.com/ded/bowser
 * MIT License | (c) Dustin Diaz 2014
 */

! function (name, definition) {
    if (typeof module != 'undefined' && module.exports) module.exports['browser'] = definition()
    else if (typeof define == 'function' && define.amd) define(definition)
    else this[name] = definition()
}('bowser', function () {
    /**
     * See useragents.js for examples of navigator.userAgent
     */

    var t = true

    function detect(ua) {

        function getFirstMatch(regex) {
            var match = ua.match(regex);
            return (match && match.length > 1 && match[1]) || '';
        }

        function getSecondMatch(regex) {
            var match = ua.match(regex);
            return (match && match.length > 1 && match[2]) || '';
        }

        var iosdevice = getFirstMatch(/(ipod|iphone|ipad)/i).toLowerCase(),
            likeAndroid = /like android/i.test(ua),
            android = !likeAndroid && /android/i.test(ua),
            edgeVersion = getFirstMatch(/edge\/(\d+(\.\d+)?)/i),
            versionIdentifier = getFirstMatch(/version\/(\d+(\.\d+)?)/i),
            tablet = /tablet/i.test(ua),
            mobile = !tablet && /[^-]mobi/i.test(ua),
            result

        if (/opera|opr/i.test(ua)) {
            result = {
                name: 'Opera',
                opera: t,
                version: versionIdentifier || getFirstMatch(/(?:opera|opr)[\s\/](\d+(\.\d+)?)/i)
            }
        }
        else if (/yabrowser/i.test(ua)) {
            result = {
                name: 'Yandex Browser',
                yandexbrowser: t,
                version: versionIdentifier || getFirstMatch(/(?:yabrowser)[\s\/](\d+(\.\d+)?)/i)
            }
        }
        else if (/windows phone/i.test(ua)) {
            result = {
                name: 'Windows Phone',
                windowsphone: t
            }
            if (edgeVersion) {
                result.msedge = t
                result.version = edgeVersion
            }
            else {
                result.msie = t
                result.version = getFirstMatch(/iemobile\/(\d+(\.\d+)?)/i)
            }
        }
        else if (/msie|trident/i.test(ua)) {
            result = {
                name: 'Internet Explorer',
                msie: t,
                version: getFirstMatch(/(?:msie |rv:)(\d+(\.\d+)?)/i)
            }
        }
        else if (/chrome.+? edge/i.test(ua)) {
            result = {
                name: 'Microsoft Edge',
                msedge: t,
                version: edgeVersion
            }
        }
        else if (/chrome|crios|crmo/i.test(ua)) {
            result = {
                name: 'Chrome',
                chrome: t,
                version: getFirstMatch(/(?:chrome|crios|crmo)\/(\d+(\.\d+)?)/i)
            }
        }
        else if (iosdevice) {
            result = {
                    name: iosdevice == 'iphone' ? 'iPhone' : iosdevice == 'ipad' ? 'iPad' : 'iPod'
                }
                // WTF: version is not part of user agent in web apps
            if (versionIdentifier) {
                result.version = versionIdentifier
            }
        }
        else if (/sailfish/i.test(ua)) {
            result = {
                name: 'Sailfish',
                sailfish: t,
                version: getFirstMatch(/sailfish\s?browser\/(\d+(\.\d+)?)/i)
            }
        }
        else if (/seamonkey\//i.test(ua)) {
            result = {
                name: 'SeaMonkey',
                seamonkey: t,
                version: getFirstMatch(/seamonkey\/(\d+(\.\d+)?)/i)
            }
        }
        else if (/firefox|iceweasel/i.test(ua)) {
            result = {
                name: 'Firefox',
                firefox: t,
                version: getFirstMatch(/(?:firefox|iceweasel)[ \/](\d+(\.\d+)?)/i)
            }
            if (/\((mobile|tablet);[^\)]*rv:[\d\.]+\)/i.test(ua)) {
                result.firefoxos = t
            }
        }
        else if (/silk/i.test(ua)) {
            result = {
                name: 'Amazon Silk',
                silk: t,
                version: getFirstMatch(/silk\/(\d+(\.\d+)?)/i)
            }
        }
        else if (android) {
            result = {
                name: 'Android',
                version: versionIdentifier
            }
        }
        else if (/phantom/i.test(ua)) {
            result = {
                name: 'PhantomJS',
                phantom: t,
                version: getFirstMatch(/phantomjs\/(\d+(\.\d+)?)/i)
            }
        }
        else if (/blackberry|\bbb\d+/i.test(ua) || /rim\stablet/i.test(ua)) {
            result = {
                name: 'BlackBerry',
                blackberry: t,
                version: versionIdentifier || getFirstMatch(/blackberry[\d]+\/(\d+(\.\d+)?)/i)
            }
        }
        else if (/(web|hpw)os/i.test(ua)) {
            result = {
                name: 'WebOS',
                webos: t,
                version: versionIdentifier || getFirstMatch(/w(?:eb)?osbrowser\/(\d+(\.\d+)?)/i)
            };
            /touchpad\//i.test(ua) && (result.touchpad = t)
        }
        else if (/bada/i.test(ua)) {
            result = {
                name: 'Bada',
                bada: t,
                version: getFirstMatch(/dolfin\/(\d+(\.\d+)?)/i)
            };
        }
        else if (/tizen/i.test(ua)) {
            result = {
                name: 'Tizen',
                tizen: t,
                version: getFirstMatch(/(?:tizen\s?)?browser\/(\d+(\.\d+)?)/i) || versionIdentifier
            };
        }
        else if (/safari/i.test(ua)) {
            result = {
                name: 'Safari',
                safari: t,
                version: versionIdentifier
            }
        }
        else {
            result = {
                name: getFirstMatch(/^(.*)\/(.*) /),
                version: getSecondMatch(/^(.*)\/(.*) /)
            };
        }

        // set webkit or gecko flag for browsers based on these engines
        if (!result.msedge && /(apple)?webkit/i.test(ua)) {
            result.name = result.name || "Webkit"
            result.webkit = t
            if (!result.version && versionIdentifier) {
                result.version = versionIdentifier
            }
        }
        else if (!result.opera && /gecko\//i.test(ua)) {
            result.name = result.name || "Gecko"
            result.gecko = t
            result.version = result.version || getFirstMatch(/gecko\/(\d+(\.\d+)?)/i)
        }

        // set OS flags for platforms that have multiple browsers
        if (!result.msedge && (android || result.silk)) {
            result.android = t
        }
        else if (iosdevice) {
            result[iosdevice] = t
            result.ios = t
        }

        // OS version extraction
        var osVersion = '';
        if (result.windowsphone) {
            osVersion = getFirstMatch(/windows phone (?:os)?\s?(\d+(\.\d+)*)/i);
        }
        else if (iosdevice) {
            osVersion = getFirstMatch(/os (\d+([_\s]\d+)*) like mac os x/i);
            osVersion = osVersion.replace(/[_\s]/g, '.');
        }
        else if (android) {
            osVersion = getFirstMatch(/android[ \/-](\d+(\.\d+)*)/i);
        }
        else if (result.webos) {
            osVersion = getFirstMatch(/(?:web|hpw)os\/(\d+(\.\d+)*)/i);
        }
        else if (result.blackberry) {
            osVersion = getFirstMatch(/rim\stablet\sos\s(\d+(\.\d+)*)/i);
        }
        else if (result.bada) {
            osVersion = getFirstMatch(/bada\/(\d+(\.\d+)*)/i);
        }
        else if (result.tizen) {
            osVersion = getFirstMatch(/tizen[\/\s](\d+(\.\d+)*)/i);
        }
        if (osVersion) {
            result.osversion = osVersion;
        }

        // device type extraction
        var osMajorVersion = osVersion.split('.')[0];
        if (tablet || iosdevice == 'ipad' || (android && (osMajorVersion == 3 || (osMajorVersion == 4 && !mobile))) || result.silk) {
            result.tablet = t
        }
        else if (mobile || iosdevice == 'iphone' || iosdevice == 'ipod' || android || result.blackberry || result.webos || result.bada) {
            result.mobile = t
        }

        // Graded Browser Support
        // http://developer.yahoo.com/yui/articles/gbs
        if (result.msedge ||
            (result.msie && result.version >= 10) ||
            (result.yandexbrowser && result.version >= 15) ||
            (result.chrome && result.version >= 20) ||
            (result.firefox && result.version >= 20.0) ||
            (result.safari && result.version >= 6) ||
            (result.opera && result.version >= 10.0) ||
            (result.ios && result.osversion && result.osversion.split(".")[0] >= 6) ||
            (result.blackberry && result.version >= 10.1)
        ) {
            result.a = t;
        }
        else if ((result.msie && result.version < 10) ||
            (result.chrome && result.version < 20) ||
            (result.firefox && result.version < 20.0) ||
            (result.safari && result.version < 6) ||
            (result.opera && result.version < 10.0) ||
            (result.ios && result.osversion && result.osversion.split(".")[0] < 6)
        ) {
            result.c = t
        }
        else result.x = t

        return result
    }

    var bowser = detect(typeof navigator !== 'undefined' ? navigator.userAgent : '')

    bowser.test = function (browserList) {
        for (var i = 0; i < browserList.length; ++i) {
            var browserItem = browserList[i];
            if (typeof browserItem === 'string') {
                if (browserItem in bowser) {
                    return true;
                }
            }
        }
        return false;
    }

    /*
     * Set our detect method to the main bowser object so we can
     * reuse it to test other user agents.
     * This is needed to implement future tests.
     */
    bowser._detect = detect;

    return bowser
});