Get Operating system and browser using JavaScript

os_browser_detection.js

var os = (function() {
    var ua = navigator.userAgent.toLowerCase();
    return {
        isWin : /windows/.test(ua),
        ismacOs :  /mac os/.test(ua)
    };
}());

var browser = (function() {
    var ua = navigator.userAgent.toLowerCase();
    return {
        isIE: /trident/.test(ua),
        isFirefox: /firefox/.test(ua),
        isChrome: /chrome/.test(ua),
        isSafari: /safari/.test(ua),
    };
}());
alert(os.isWin);
alert(os.isChrome);