A JavaScript function that extracts the browser name and version number from user agent string. Recognized browsers: Firefox, Internet Explorer, Opera, Chrome, and Safari.

identify-browser.js

/**
 * Extracts the browser name and version number from user agent string.
 *
 * @param userAgent
 *            The user agent string to parse. If not specified, the contents of
 *            navigator.userAgent are parsed.
 * @param elements
 *            How many elements of the version number should be returned. A
 *            value of 0 means the whole version. If not specified, defaults to
 *            2 (major and minor release number).
 * @return A string containing the browser name and version number, or null if
 *         the user agent string is unknown.
 */
function identifyBrowser(userAgent, elements) {
    var regexps = {
            'Chrome': [ /Chrome\/(\S+)/ ],
            'Firefox': [ /Firefox\/(\S+)/ ],
            'MSIE': [ /MSIE (\S+);/ ],
            'Opera': [
                /Opera\/.*?Version\/(\S+)/,     /* Opera 10 */
                /Opera\/(\S+)/                  /* Opera 9 and older */
            ],
            'Safari': [ /Version\/(\S+).*?Safari\// ]
        },
        re, m, browser, version;
 
    if (userAgent === undefined)
        userAgent = navigator.userAgent;
 
    if (elements === undefined)
        elements = 2;
    else if (elements === 0)
        elements = 1337;
 
    for (browser in regexps)
        while (re = regexps[browser].shift())
            if (m = userAgent.match(re)) {
                version = (m[1].match(new RegExp('[^.]+(?:\.[^.]+){0,' + --elements + '}')))[0];
                return browser + ' ' + version;
            }
 
    return null;
}

This might be helpful: Default parameters

It doesn't resolve for Edge Browser.