[javascript] How to find the operating system version using JavaScript?

How can I find the OS name and OS version using JavaScript?

I started to write a Script to read OS and browser version that can be tested on Fiddle. Feel free to use and extend.
Breaking Change:
Since September 2020 the new Edge gets detected. So 'Microsoft Edge' is the new version based on Chromium and the old Edge is now detected as 'Microsoft Legacy Edge'!

/**
 * JavaScript Client Detection
 * (C) viazenetti GmbH (Christian Ludwig)
 */
(function (window) {
    {
        var unknown = '-';

        // screen
        var screenSize = '';
        if (screen.width) {
            width = (screen.width) ? screen.width : '';
            height = (screen.height) ? screen.height : '';
            screenSize += '' + width + " x " + height;
        }

        // browser
        var nVer = navigator.appVersion;
        var nAgt = navigator.userAgent;
        var browser = navigator.appName;
        var version = '' + parseFloat(navigator.appVersion);
        var majorVersion = parseInt(navigator.appVersion, 10);
        var nameOffset, verOffset, ix;

        // Opera
        if ((verOffset = nAgt.indexOf('Opera')) != -1) {
            browser = 'Opera';
            version = nAgt.substring(verOffset + 6);
            if ((verOffset = nAgt.indexOf('Version')) != -1) {
                version = nAgt.substring(verOffset + 8);
            }
        }
        // Opera Next
        if ((verOffset = nAgt.indexOf('OPR')) != -1) {
            browser = 'Opera';
            version = nAgt.substring(verOffset + 4);
        }
        // Legacy Edge
        else if ((verOffset = nAgt.indexOf('Edge')) != -1) {
            browser = 'Microsoft Legacy Edge';
            version = nAgt.substring(verOffset + 5);
        } 
        // Edge (Chromium)
        else if ((verOffset = nAgt.indexOf('Edg')) != -1) {
            browser = 'Microsoft Edge';
            version = nAgt.substring(verOffset + 4);
        }
        // MSIE
        else if ((verOffset = nAgt.indexOf('MSIE')) != -1) {
            browser = 'Microsoft Internet Explorer';
            version = nAgt.substring(verOffset + 5);
        }
        // Chrome
        else if ((verOffset = nAgt.indexOf('Chrome')) != -1) {
            browser = 'Chrome';
            version = nAgt.substring(verOffset + 7);
        }
        // Safari
        else if ((verOffset = nAgt.indexOf('Safari')) != -1) {
            browser = 'Safari';
            version = nAgt.substring(verOffset + 7);
            if ((verOffset = nAgt.indexOf('Version')) != -1) {
                version = nAgt.substring(verOffset + 8);
            }
        }
        // Firefox
        else if ((verOffset = nAgt.indexOf('Firefox')) != -1) {
            browser = 'Firefox';
            version = nAgt.substring(verOffset + 8);
        }
        // MSIE 11+
        else if (nAgt.indexOf('Trident/') != -1) {
            browser = 'Microsoft Internet Explorer';
            version = nAgt.substring(nAgt.indexOf('rv:') + 3);
        }
        // Other browsers
        else if ((nameOffset = nAgt.lastIndexOf(' ') + 1) < (verOffset = nAgt.lastIndexOf('/'))) {
            browser = nAgt.substring(nameOffset, verOffset);
            version = nAgt.substring(verOffset + 1);
            if (browser.toLowerCase() == browser.toUpperCase()) {
                browser = navigator.appName;
            }
        }
        // trim the version string
        if ((ix = version.indexOf(';')) != -1) version = version.substring(0, ix);
        if ((ix = version.indexOf(' ')) != -1) version = version.substring(0, ix);
        if ((ix = version.indexOf(')')) != -1) version = version.substring(0, ix);

        majorVersion = parseInt('' + version, 10);
        if (isNaN(majorVersion)) {
            version = '' + parseFloat(navigator.appVersion);
            majorVersion = parseInt(navigator.appVersion, 10);
        }

        // mobile version
        var mobile = /Mobile|mini|Fennec|Android|iP(ad|od|hone)/.test(nVer);

        // cookie
        var cookieEnabled = (navigator.cookieEnabled) ? true : false;

        if (typeof navigator.cookieEnabled == 'undefined' && !cookieEnabled) {
            document.cookie = 'testcookie';
            cookieEnabled = (document.cookie.indexOf('testcookie') != -1) ? true : false;
        }

        // system
        var os = unknown;
        var clientStrings = [
            {s:'Windows 10', r:/(Windows 10.0|Windows NT 10.0)/},
            {s:'Windows 8.1', r:/(Windows 8.1|Windows NT 6.3)/},
            {s:'Windows 8', r:/(Windows 8|Windows NT 6.2)/},
            {s:'Windows 7', r:/(Windows 7|Windows NT 6.1)/},
            {s:'Windows Vista', r:/Windows NT 6.0/},
            {s:'Windows Server 2003', r:/Windows NT 5.2/},
            {s:'Windows XP', r:/(Windows NT 5.1|Windows XP)/},
            {s:'Windows 2000', r:/(Windows NT 5.0|Windows 2000)/},
            {s:'Windows ME', r:/(Win 9x 4.90|Windows ME)/},
            {s:'Windows 98', r:/(Windows 98|Win98)/},
            {s:'Windows 95', r:/(Windows 95|Win95|Windows_95)/},
            {s:'Windows NT 4.0', r:/(Windows NT 4.0|WinNT4.0|WinNT|Windows NT)/},
            {s:'Windows CE', r:/Windows CE/},
            {s:'Windows 3.11', r:/Win16/},
            {s:'Android', r:/Android/},
            {s:'Open BSD', r:/OpenBSD/},
            {s:'Sun OS', r:/SunOS/},
            {s:'Chrome OS', r:/CrOS/},
            {s:'Linux', r:/(Linux|X11(?!.*CrOS))/},
            {s:'iOS', r:/(iPhone|iPad|iPod)/},
            {s:'Mac OS X', r:/Mac OS X/},
            {s:'Mac OS', r:/(Mac OS|MacPPC|MacIntel|Mac_PowerPC|Macintosh)/},
            {s:'QNX', r:/QNX/},
            {s:'UNIX', r:/UNIX/},
            {s:'BeOS', r:/BeOS/},
            {s:'OS/2', r:/OS\/2/},
            {s:'Search Bot', r:/(nuhk|Googlebot|Yammybot|Openbot|Slurp|MSNBot|Ask Jeeves\/Teoma|ia_archiver)/}
        ];
        for (var id in clientStrings) {
            var cs = clientStrings[id];
            if (cs.r.test(nAgt)) {
                os = cs.s;
                break;
            }
        }

        var osVersion = unknown;

        if (/Windows/.test(os)) {
            osVersion = /Windows (.*)/.exec(os)[1];
            os = 'Windows';
        }

        switch (os) {
            case 'Mac OS':
            case 'Mac OS X':
            case 'Android':
                osVersion = /(?:Android|Mac OS|Mac OS X|MacPPC|MacIntel|Mac_PowerPC|Macintosh) ([\.\_\d]+)/.exec(nAgt)[1];
                break;

            case 'iOS':
                osVersion = /OS (\d+)_(\d+)_?(\d+)?/.exec(nVer);
                osVersion = osVersion[1] + '.' + osVersion[2] + '.' + (osVersion[3] | 0);
                break;
        }
        
        // flash (you'll need to include swfobject)
        /* script src="//ajax.googleapis.com/ajax/libs/swfobject/2.2/swfobject.js" */
        var flashVersion = 'no check';
        if (typeof swfobject != 'undefined') {
            var fv = swfobject.getFlashPlayerVersion();
            if (fv.major > 0) {
                flashVersion = fv.major + '.' + fv.minor + ' r' + fv.release;
            }
            else  {
                flashVersion = unknown;
            }
        }
    }

    window.jscd = {
        screen: screenSize,
        browser: browser,
        browserVersion: version,
        browserMajorVersion: majorVersion,
        mobile: mobile,
        os: os,
        osVersion: osVersion,
        cookies: cookieEnabled,
        flashVersion: flashVersion
    };
}(this));

alert(
    'OS: ' + jscd.os +' '+ jscd.osVersion + '\n' +
    'Browser: ' + jscd.browser +' '+ jscd.browserMajorVersion +
      ' (' + jscd.browserVersion + ')\n' + 
    'Mobile: ' + jscd.mobile + '\n' +
    'Flash: ' + jscd.flashVersion + '\n' +
    'Cookies: ' + jscd.cookies + '\n' +
    'Screen Size: ' + jscd.screen + '\n\n' +
    'Full User Agent: ' + navigator.userAgent
);

You can use this javascript function to check users' OS simply

  function getOS() {
  var userAgent = window.navigator.userAgent,
      platform = window.navigator.platform,
      macosPlatforms = ['Macintosh', 'MacIntel', 'MacPPC', 'Mac68K'],
      windowsPlatforms = ['Win32', 'Win64', 'Windows', 'WinCE'],
      iosPlatforms = ['iPhone', 'iPad', 'iPod'],
      os = null;

  if (macosPlatforms.indexOf(platform) !== -1) {
    os = 'Mac OS';
  } else if (iosPlatforms.indexOf(platform) !== -1) {
    os = 'iOS';
  } else if (windowsPlatforms.indexOf(platform) !== -1) {
    os = 'Windows';
  } else if (/Android/.test(userAgent)) {
    os = 'Android';
  } else if (!os && /Linux/.test(platform)) {
    os = 'Linux';
  }

  return os;
}

alert(getOS());

I can't comment on @Ian Ippolito answer (because I would have if I had the rep) but according to the document his comment linked, I'm fairly certain you can find the Chrome version for IOS. https://developer.chrome.com/multidevice/user-agent?hl=ja lists the UA as: Mozilla/5.0 (iPhone; CPU iPhone OS 10_3 like Mac OS X) AppleWebKit/602.1.50 (KHTML, like Gecko) CriOS/56.0.2924.75 Mobile/14E5239e Safari/602.1

So this should work:

if ((verOffset = nAgt.indexOf('CriOS')) != -1) {
                //Chrome on iPad spoofing Safari...correct it.
                browser = 'Chrome';
                version = nAgt.substring(verOffset + 6);//should get the criOS ver.
            }

Haven't been able to test (otherwise I would have improved his answer) it to make sure since my iPad is at home and I'm at work, but I thought I'd put it out there.

platform.js seems like a good one file library to do this.

Usage example:

// on IE10 x86 platform preview running in IE7 compatibility mode on Windows 7 64 bit edition
platform.name; // 'IE'
platform.version; // '10.0'
platform.layout; // 'Trident'
platform.os; // 'Windows Server 2008 R2 / 7 x64'
platform.description; // 'IE 10.0 x86 (platform preview; running in IE 7 mode) on Windows Server 2008 R2 / 7 x64'

// or on an iPad
platform.name; // 'Safari'
platform.version; // '5.1'
platform.product; // 'iPad'
platform.manufacturer; // 'Apple'
platform.layout; // 'WebKit'
platform.os; // 'iOS 5.0'
platform.description; // 'Safari 5.1 on Apple iPad (iOS 5.0)'

// or parsing a given UA string
var info = platform.parse('Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7.2; en; rv:2.0) Gecko/20100101 Firefox/4.0 Opera 11.52');
info.name; // 'Opera'
info.version; // '11.52'
info.layout; // 'Presto'
info.os; // 'Mac OS X 10.7.2'
info.description; // 'Opera 11.52 (identifying as Firefox 4.0) on Mac OS X 10.7.2'

@Ludwig 's solution was brilliant. A couple of fixes (which didn't have to do with operating system, and I couldn't place as a comment on his original posting because this is too long):

1. IE 11 no longer identifies itself as MS IE.
2. Chrome on IOS spoofs itself as Safari

Here they are:

(function (window) {
    {
    /* test cases
        alert(
            'browserInfo result: OS: ' + browserInfo.os +' '+ browserInfo.osVersion + '\n'+
                'Browser: ' + browserInfo.browser +' '+ browserInfo.browserVersion + '\n' +
                'Mobile: ' + browserInfo.mobile + '\n' +
                'Cookies: ' + browserInfo.cookies + '\n' +
                'Screen Size: ' + browserInfo.screen
        );
    */
        var unknown = 'Unknown';

        // screen
        var screenSize = '';
        if (screen.width) {
            width = (screen.width) ? screen.width : '';
            height = (screen.height) ? screen.height : '';
            screenSize += '' + width + " x " + height;
        }

        //browser
        var nVer = navigator.appVersion;
        var nAgt = navigator.userAgent;
        var browser = navigator.appName;
        var version = '' + parseFloat(navigator.appVersion);
        var majorVersion = parseInt(navigator.appVersion, 10);
        var nameOffset, verOffset, ix;

        // Opera
        if ((verOffset = nAgt.indexOf('Opera')) != -1) {
            browser = 'Opera';
            version = nAgt.substring(verOffset + 6);
            if ((verOffset = nAgt.indexOf('Version')) != -1) {
                version = nAgt.substring(verOffset + 8);
            }
        }
        // MSIE
        else if ((verOffset = nAgt.indexOf('MSIE')) != -1) {
            browser = 'Microsoft Internet Explorer';
            version = nAgt.substring(verOffset + 5);
        }

        //IE 11 no longer identifies itself as MS IE, so trap it
        //http://stackoverflow.com/questions/17907445/how-to-detect-ie11
        else if ((browser == 'Netscape') && (nAgt.indexOf('Trident/') != -1)) {

            browser = 'Microsoft Internet Explorer';
            version = nAgt.substring(verOffset + 5);
            if ((verOffset = nAgt.indexOf('rv:')) != -1) {
                version = nAgt.substring(verOffset + 3);
            }

        }

        // Chrome
        else if ((verOffset = nAgt.indexOf('Chrome')) != -1) {
            browser = 'Chrome';
            version = nAgt.substring(verOffset + 7);
        }
        // Safari
        else if ((verOffset = nAgt.indexOf('Safari')) != -1) {
            browser = 'Safari';
            version = nAgt.substring(verOffset + 7);
            if ((verOffset = nAgt.indexOf('Version')) != -1) {
                version = nAgt.substring(verOffset + 8);
            }

            // Chrome on iPad identifies itself as Safari. Actual results do not match what Google claims
            //  at: https://developers.google.com/chrome/mobile/docs/user-agent?hl=ja
            //  No mention of chrome in the user agent string. However it does mention CriOS, which presumably
            //  can be keyed on to detect it.
            if (nAgt.indexOf('CriOS') != -1) {
                //Chrome on iPad spoofing Safari...correct it.
                browser = 'Chrome';
                //Don't believe there is a way to grab the accurate version number, so leaving that for now.
            }
        }
        // Firefox
        else if ((verOffset = nAgt.indexOf('Firefox')) != -1) {
            browser = 'Firefox';
            version = nAgt.substring(verOffset + 8);
        }
        // Other browsers
        else if ((nameOffset = nAgt.lastIndexOf(' ') + 1) < (verOffset = nAgt.lastIndexOf('/'))) {
            browser = nAgt.substring(nameOffset, verOffset);
            version = nAgt.substring(verOffset + 1);
            if (browser.toLowerCase() == browser.toUpperCase()) {
                browser = navigator.appName;
            }
        }
        // trim the version string
        if ((ix = version.indexOf(';')) != -1) version = version.substring(0, ix);
        if ((ix = version.indexOf(' ')) != -1) version = version.substring(0, ix);
        if ((ix = version.indexOf(')')) != -1) version = version.substring(0, ix);

        majorVersion = parseInt('' + version, 10);
        if (isNaN(majorVersion)) {
            version = '' + parseFloat(navigator.appVersion);
            majorVersion = parseInt(navigator.appVersion, 10);
        }

        // mobile version
        var mobile = /Mobile|mini|Fennec|Android|iP(ad|od|hone)/.test(nVer);

        // cookie
        var cookieEnabled = (navigator.cookieEnabled) ? true : false;

        if (typeof navigator.cookieEnabled == 'undefined' && !cookieEnabled) {
            document.cookie = 'testcookie';
            cookieEnabled = (document.cookie.indexOf('testcookie') != -1) ? true : false;
        }

        // system
        var os = unknown;
        var clientStrings = [
            {s:'Windows 3.11', r:/Win16/},
            {s:'Windows 95', r:/(Windows 95|Win95|Windows_95)/},
            {s:'Windows ME', r:/(Win 9x 4.90|Windows ME)/},
            {s:'Windows 98', r:/(Windows 98|Win98)/},
            {s:'Windows CE', r:/Windows CE/},
            {s:'Windows 2000', r:/(Windows NT 5.0|Windows 2000)/},
            {s:'Windows XP', r:/(Windows NT 5.1|Windows XP)/},
            {s:'Windows Server 2003', r:/Windows NT 5.2/},
            {s:'Windows Vista', r:/Windows NT 6.0/},
            {s:'Windows 7', r:/(Windows 7|Windows NT 6.1)/},
            {s:'Windows 8.1', r:/(Windows 8.1|Windows NT 6.3)/},
            {s:'Windows 8', r:/(Windows 8|Windows NT 6.2)/},
            {s:'Windows NT 4.0', r:/(Windows NT 4.0|WinNT4.0|WinNT|Windows NT)/},
            {s:'Windows ME', r:/Windows ME/},
            {s:'Android', r:/Android/},
            {s:'Open BSD', r:/OpenBSD/},
            {s:'Sun OS', r:/SunOS/},
            {s:'Linux', r:/(Linux|X11)/},
            {s:'iOS', r:/(iPhone|iPad|iPod)/},
            {s:'Mac OS X', r:/Mac OS X/},
            {s:'Mac OS', r:/(MacPPC|MacIntel|Mac_PowerPC|Macintosh)/},
            {s:'QNX', r:/QNX/},
            {s:'UNIX', r:/UNIX/},
            {s:'BeOS', r:/BeOS/},
            {s:'OS/2', r:/OS\/2/},
            {s:'Search Bot', r:/(nuhk|Googlebot|Yammybot|Openbot|Slurp|MSNBot|Ask Jeeves\/Teoma|ia_archiver)/}
        ];
        for (var id in clientStrings) {
            var cs = clientStrings[id];
            if (cs.r.test(nAgt)) {
                os = cs.s;
                break;
            }
        }

        var osVersion = unknown;

        if (/Windows/.test(os)) {
            osVersion = /Windows (.*)/.exec(os)[1];
            os = 'Windows';
        }

        switch (os) {
            case 'Mac OS X':
                osVersion = /Mac OS X (10[\.\_\d]+)/.exec(nAgt)[1];
                break;

            case 'Android':
                osVersion = /Android ([\.\_\d]+)/.exec(nAgt)[1];
                break;

            case 'iOS':
                osVersion = /OS (\d+)_(\d+)_?(\d+)?/.exec(nVer);
                osVersion = osVersion[1] + '.' + osVersion[2] + '.' + (osVersion[3] | 0);
                break;

        }
    }

    window.browserInfo = {
        screen: screenSize,
        browser: browser,
        browserVersion: version,
        mobile: mobile,
        os: os,
        osVersion: osVersion,
        cookies: cookieEnabled
    };
}(this));

I've created a library for parsing User Agent strings called Voodoo. But be aware that this should not be used instead of feature detection.

What Voodoo does, is that it parses the userAgent string, which is found in the Navigator object (window.navigator). It's not all browsers that passes a reliable userAgent string, so even though it's the normal way to do it, the userAgent can not always be trusted.

You can find the OS name and version in the navigator object, as others have answered. The standard, cross-browser place to find this information is in the navigator.userAgent property. However, user agent strings vary widely by OS and browser.

So, I created a script to encapsulate this logic and report on the most common OSes and browsers in a familiar way, like http://www.whatsmybrowser.org.

I open-sourced the script and uploaded it to github, https://github.com/keithws/browser-report. Pull requests are welcome!

Hey for a quick solution you can consider the following library : UAPARSER - https://www.npmjs.com/package/ua-parser-js

example :

<script type="text/javascript" src="ua-parser.min.js"></script>
<script type="text/javascript">

var parser = new UAParser();
console.log(parser.getOS()) // will log  {name: "", version:""}

you can also install the library via npm, and import it like this:

import { UAParser } from 'ua-parser-js';
let parser = new UAParser();
parser.getOS();

the library is a JS based user agent string parser (window.navigator.userAgent is the user agent on browser) , so you can get with it other details aswell such as Browser,device,engines etc..and it can work with node js as well.

if you need typing for the library : https://www.npmjs.com/package/@types/ua-parser-js

I fork @Ludwig code and remove necessity of swfobject.

I just use swfobject code for detect flash version.

/**
 * JavaScript Client Detection
 * (C) viazenetti GmbH (Christian Ludwig)
 */
(function (window) {
    {
    var unknown = '-';

    // screen
    var screenSize = '';
    if (screen.width) {
        width = (screen.width) ? screen.width : '';
        height = (screen.height) ? screen.height : '';
        screenSize += '' + width + " x " + height;
    }

    //browser
    var nVer = navigator.appVersion;
    var nAgt = navigator.userAgent;
    var browser = navigator.appName;
    var version = '' + parseFloat(navigator.appVersion);
    var majorVersion = parseInt(navigator.appVersion, 10);
    var nameOffset, verOffset, ix;

    // Opera
    if ((verOffset = nAgt.indexOf('Opera')) != -1) {
        browser = 'Opera';
        version = nAgt.substring(verOffset + 6);
        if ((verOffset = nAgt.indexOf('Version')) != -1) {
        version = nAgt.substring(verOffset + 8);
        }
    }
    // MSIE
    else if ((verOffset = nAgt.indexOf('MSIE')) != -1) {
        browser = 'Microsoft Internet Explorer';
        version = nAgt.substring(verOffset + 5);
    }
    // Chrome
    else if ((verOffset = nAgt.indexOf('Chrome')) != -1) {
        browser = 'Chrome';
        version = nAgt.substring(verOffset + 7);
    }
    // Safari
    else if ((verOffset = nAgt.indexOf('Safari')) != -1) {
        browser = 'Safari';
        version = nAgt.substring(verOffset + 7);
        if ((verOffset = nAgt.indexOf('Version')) != -1) {
        version = nAgt.substring(verOffset + 8);
        }
    }
    // Firefox
    else if ((verOffset = nAgt.indexOf('Firefox')) != -1) {
        browser = 'Firefox';
        version = nAgt.substring(verOffset + 8);
    }
    // MSIE 11+
    else if (nAgt.indexOf('Trident/') != -1) {
        browser = 'Microsoft Internet Explorer';
        version = nAgt.substring(nAgt.indexOf('rv:') + 3);
    }
    // Other browsers
    else if ((nameOffset = nAgt.lastIndexOf(' ') + 1) < (verOffset = nAgt.lastIndexOf('/'))) {
        browser = nAgt.substring(nameOffset, verOffset);
        version = nAgt.substring(verOffset + 1);
        if (browser.toLowerCase() == browser.toUpperCase()) {
        browser = navigator.appName;
        }
    }
    // trim the version string
    if ((ix = version.indexOf(';')) != -1) version = version.substring(0, ix);
    if ((ix = version.indexOf(' ')) != -1) version = version.substring(0, ix);
    if ((ix = version.indexOf(')')) != -1) version = version.substring(0, ix);

    majorVersion = parseInt('' + version, 10);
    if (isNaN(majorVersion)) {
        version = '' + parseFloat(navigator.appVersion);
        majorVersion = parseInt(navigator.appVersion, 10);
    }

    // mobile version
    var mobile = /Mobile|mini|Fennec|Android|iP(ad|od|hone)/.test(nVer);

    // cookie
    var cookieEnabled = (navigator.cookieEnabled) ? true : false;

    if (typeof navigator.cookieEnabled == 'undefined' && !cookieEnabled) {
        document.cookie = 'testcookie';
        cookieEnabled = (document.cookie.indexOf('testcookie') != -1) ? true : false;
    }

    // system
    var os = unknown;
    var clientStrings = [
        {s:'Windows 10', r:/(Windows 10.0|Windows NT 10.0)/},
        {s:'Windows 8.1', r:/(Windows 8.1|Windows NT 6.3)/},
        {s:'Windows 8', r:/(Windows 8|Windows NT 6.2)/},
        {s:'Windows 7', r:/(Windows 7|Windows NT 6.1)/},
        {s:'Windows Vista', r:/Windows NT 6.0/},
        {s:'Windows Server 2003', r:/Windows NT 5.2/},
        {s:'Windows XP', r:/(Windows NT 5.1|Windows XP)/},
        {s:'Windows 2000', r:/(Windows NT 5.0|Windows 2000)/},
        {s:'Windows ME', r:/(Win 9x 4.90|Windows ME)/},
        {s:'Windows 98', r:/(Windows 98|Win98)/},
        {s:'Windows 95', r:/(Windows 95|Win95|Windows_95)/},
        {s:'Windows NT 4.0', r:/(Windows NT 4.0|WinNT4.0|WinNT|Windows NT)/},
        {s:'Windows CE', r:/Windows CE/},
        {s:'Windows 3.11', r:/Win16/},
        {s:'Android', r:/Android/},
        {s:'Open BSD', r:/OpenBSD/},
        {s:'Sun OS', r:/SunOS/},
        {s:'Linux', r:/(Linux|X11)/},
        {s:'iOS', r:/(iPhone|iPad|iPod)/},
        {s:'Mac OS X', r:/Mac OS X/},
        {s:'Mac OS', r:/(MacPPC|MacIntel|Mac_PowerPC|Macintosh)/},
        {s:'QNX', r:/QNX/},
        {s:'UNIX', r:/UNIX/},
        {s:'BeOS', r:/BeOS/},
        {s:'OS/2', r:/OS\/2/},
        {s:'Search Bot', r:/(nuhk|Googlebot|Yammybot|Openbot|Slurp|MSNBot|Ask Jeeves\/Teoma|ia_archiver)/}
    ];
    for (var id in clientStrings) {
        var cs = clientStrings[id];
        if (cs.r.test(nAgt)) {
        os = cs.s;
        break;
        }
    }

    var osVersion = unknown;

    if (/Windows/.test(os)) {
        osVersion = /Windows (.*)/.exec(os)[1];
        os = 'Windows';
    }

    switch (os) {
        case 'Mac OS X':
        osVersion = /Mac OS X (10[\.\_\d]+)/.exec(nAgt)[1];
        break;

        case 'Android':
        osVersion = /Android ([\.\_\d]+)/.exec(nAgt)[1];
        break;

        case 'iOS':
        osVersion = /OS (\d+)_(\d+)_?(\d+)?/.exec(nVer);
        osVersion = osVersion[1] + '.' + osVersion[2] + '.' + (osVersion[3] | 0);
        break;
    }

    var flashVersion = 'no check', d, fv = [];
    if (typeof navigator.plugins !== 'undefined' && typeof navigator.plugins["Shockwave Flash"] === "object") {
        d = navigator.plugins["Shockwave Flash"].description;
        if (d && !(typeof navigator.mimeTypes !== 'undefined' && navigator.mimeTypes["application/x-shockwave-flash"] && !navigator.mimeTypes["application/x-shockwave-flash"].enabledPlugin)) { // navigator.mimeTypes["application/x-shockwave-flash"].enabledPlugin indicates whether plug-ins are enabled or disabled in Safari 3+
        d = d.replace(/^.*\s+(\S+\s+\S+$)/, "$1");
        fv[0] = parseInt(d.replace(/^(.*)\..*$/, "$1"), 10);
        fv[1] = parseInt(d.replace(/^.*\.(.*)\s.*$/, "$1"), 10);
        fv[2] = /[a-zA-Z]/.test(d) ? parseInt(d.replace(/^.*[a-zA-Z]+(.*)$/, "$1"), 10) : 0;
        }
    } else if (typeof window.ActiveXObject !== 'undefined') {
        try {
        var a = new ActiveXObject("ShockwaveFlash.ShockwaveFlash");
        if (a) { // a will return null when ActiveX is disabled
            d = a.GetVariable("$version");
            if (d) {
            d = d.split(" ")[1].split(",");
            fv = [parseInt(d[0], 10), parseInt(d[1], 10), parseInt(d[2], 10)];
            }
        }
        }
        catch(e) {}
    }
    if (fv.length) {
        flashVersion = fv[0] + '.' + fv[1] + ' r' + fv[2];
    }    
    }

    window.jscd = {
    screen: screenSize,
    browser: browser,
    browserVersion: version,
    mobile: mobile,
    os: os,
    osVersion: osVersion,
    cookies: cookieEnabled,
    flashVersion: flashVersion
    };
}(this));

alert(
    'OS: ' + jscd.os +' '+ jscd.osVersion + '\n'+
    'Browser: ' + jscd.browser +' '+ jscd.browserVersion + '\n' + 
    'Mobile: ' + jscd.mobile + '\n' +
    'Flash: ' + jscd.flashVersion + '\n' +
    'Cookies: ' + jscd.cookies + '\n' +
    'Screen Size: ' + jscd.screen + '\n\n' +
    'Full User Agent: ' + navigator.userAgent
);

Use detectOS.js:

var Detect = {
    init: function () {
        this.OS = this.searchString(this.dataOS);
    },
    searchString: function (data) {
        for (var i=0;i<data.length;i++) {
            var dataString = data[i].string;
            var dataProp = data[i].prop;
            if (dataString) {
                if (dataString.indexOf(data[i].subString) != -1)
                    return data[i].identity;
            }
            else if (dataProp)
                return data[i].identity;
        }
    },
    dataOS : [
        {
            string: navigator.platform,
            subString: 'Win',
            identity: 'Windows'
        },
        {
            string: navigator.platform,
            subString: 'Mac',
            identity: 'macOS'
        },
        {
            string: navigator.userAgent,
            subString: 'iPhone',
            identity: 'iOS'
        },
        {
            string: navigator.userAgent,
            subString: 'iPad',
            identity: 'iOS'
        },
        {
            string: navigator.userAgent,
            subString: 'iPod',
            identity: 'iOS'
        },
        {
            string: navigator.userAgent,
            subString: 'Android',
            identity: 'Android'
        },
        {
            string: navigator.platform,
            subString: 'Linux',
            identity: 'Linux'
        }
    ]
};

Detect.init();

console.log("We know your OS – it's " + Detect.OS + ". We know everything about you.");

var OSName = "Unknown";
if (window.navigator.userAgent.indexOf("Windows NT 10.0")!= -1) OSName="Windows 10";
if (window.navigator.userAgent.indexOf("Windows NT 6.3") != -1) OSName="Windows 8.1";
if (window.navigator.userAgent.indexOf("Windows NT 6.2") != -1) OSName="Windows 8";
if (window.navigator.userAgent.indexOf("Windows NT 6.1") != -1) OSName="Windows 7";
if (window.navigator.userAgent.indexOf("Windows NT 6.0") != -1) OSName="Windows Vista";
if (window.navigator.userAgent.indexOf("Windows NT 5.1") != -1) OSName="Windows XP";
if (window.navigator.userAgent.indexOf("Windows NT 5.0") != -1) OSName="Windows 2000";
if (window.navigator.userAgent.indexOf("Mac")            != -1) OSName="Mac/iOS";
if (window.navigator.userAgent.indexOf("X11")            != -1) OSName="UNIX";
if (window.navigator.userAgent.indexOf("Linux")          != -1) OSName="Linux";

JavaScript have access to the window.navigator.platform - a string representing the platform of the browser: https://developer.mozilla.org/en-US/docs/Web/API/NavigatorID/platform

Use it to extract whatever details you need (and can). Note that there are no guarantees that the client actually uses that platform since this can easily be modified in many ways.