Detect Exact Os Version from Browser

    var nVer = navigator.appVersion;

    var nAgt = navigator.userAgent;

    var browserName  = navigator.appName;

    var fullVersion  = ''+parseFloat(navigator.appVersion); 

    var majorVersion = parseInt(navigator.appVersion,10);

    var nameOffset,verOffset,ix;

    

    // In Opera, the true version is after "Opera" or after "Version"

    if ((verOffset=nAgt.indexOf("Opera"))!=-1) {

     browserName = "Opera";

     fullVersion = nAgt.substring(verOffset+6);

     if ((verOffset=nAgt.indexOf("Version"))!=-1) 

       fullVersion = nAgt.substring(verOffset+8);

    }

    // In MSIE, the true version is after "MSIE" in userAgent

    else if ((verOffset=nAgt.indexOf("MSIE"))!=-1) {

     browserName = "Microsoft Internet Explorer";

     fullVersion = nAgt.substring(verOffset+5);

    }

    // In Chrome, the true version is after "Chrome" 

    else if ((verOffset=nAgt.indexOf("Chrome"))!=-1) {

     browserName = "Chrome";

     fullVersion = nAgt.substring(verOffset+7);

    }

    // In Safari, the true version is after "Safari" or after "Version" 

    else if ((verOffset=nAgt.indexOf("Safari"))!=-1) {

     browserName = "Safari";

     fullVersion = nAgt.substring(verOffset+7);

     if ((verOffset=nAgt.indexOf("Version"))!=-1) 

       fullVersion = nAgt.substring(verOffset+8);

    }

    // In Firefox, the true version is after "Firefox" 

    else if ((verOffset=nAgt.indexOf("Firefox"))!=-1) {

     browserName = "Firefox";

     fullVersion = nAgt.substring(verOffset+8);

    }

    // In most other browsers, "name/version" is at the end of userAgent 

    else if ( (nameOffset=nAgt.lastIndexOf(' ')+1) < 

              (verOffset=nAgt.lastIndexOf('/')) ) 

    {

     browserName = nAgt.substring(nameOffset,verOffset);

     fullVersion = nAgt.substring(verOffset+1);

     if (browserName.toLowerCase()==browserName.toUpperCase()) {

      browserName = navigator.appName;

     }

    }

    // trim the fullVersion string at semicolon/space if present

    if ((ix=fullVersion.indexOf(";"))!=-1)

       fullVersion=fullVersion.substring(0,ix);

    if ((ix=fullVersion.indexOf(" "))!=-1)

       fullVersion=fullVersion.substring(0,ix);

    

    majorVersion = parseInt(''+fullVersion,10);

    if (isNaN(majorVersion)) {

     fullVersion  = ''+parseFloat(navigator.appVersion); 

     majorVersion = parseInt(navigator.appVersion,10);

    }

    

    document.write(''

     +'Browser name  = '+browserName+'<br>'

     +'Full version  = '+fullVersion+'<br>'

     +'Major version = '+majorVersion+'<br>'

     +'navigator.appName = '+navigator.appName+'<br>'

     +'navigator.userAgent = '+navigator.userAgent+'<br>'

    )


    // This script sets OSName variable as follows:

    // "Windows"    for all versions of Windows

    // "MacOS"      for all versions of Macintosh OS

    // "Linux"      for all versions of Linux

    // "UNIX"       for all other UNIX flavors 

    // "Unknown OS" indicates failure to detect the OS

    

    var OSName="Unknown OS";

    if (navigator.appVersion.indexOf("Win")!=-1) OSName="Windows";

    if (navigator.appVersion.indexOf("Mac")!=-1) OSName="MacOS";

    if (navigator.appVersion.indexOf("X11")!=-1) OSName="UNIX";

    if (navigator.appVersion.indexOf("Linux")!=-1) OSName="Linux";

    

    document.write('Your OS: '+OSName);

Detect the type of OS version in browser using javascript

var v = navigator.userAgent.match(/Mac OS X ([\d_]+)/)
if(v!=null && v[1] == "10_8_2") {
    alert("U r not support!");
}

How can you detect the version of a browser?

You can see what the browser says, and use that information for logging or testing multiple browsers.

navigator.sayswho= (function(){
    var ua= navigator.userAgent;
    var tem; 
    var M= ua.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || [];
    if(/trident/i.test(M[1])){
        tem=  /\brv[ :]+(\d+)/g.exec(ua) || [];
        return 'IE '+(tem[1] || '');
    }
    if(M[1]=== 'Chrome'){
        tem= ua.match(/\b(OPR|Edge)\/(\d+)/);
        if(tem!= null) return tem.slice(1).join(' ').replace('OPR', 'Opera');
    }
    M= M[2]? [M[1], M[2]]: [navigator.appName, navigator.appVersion, '-?'];
    if((tem= ua.match(/version\/(\d+)/i))!= null) M.splice(1, 1, tem[1]);
    return M.join(' ');
})();

console.log(navigator.sayswho); // outputs: `Chrome 62`

echo $_SERVER['HTTP_USER_AGENT'] . "\n\n";

$browser = get_browser(null, true);
print_r($browser);

Array
(
    [browser_name_regex] => ^mozilla/5\.0 (windows; .; windows nt 5\.1; .*rv:.*) gecko/.* firefox/0\.9.*$
    [browser_name_pattern] => Mozilla/5.0 (Windows; ?; Windows NT 5.1; *rv:*) Gecko/* Firefox/0.9*/
    [parent] => Firefox 0.9
    [platform] => WinXP
    [browser] => Firefox
    [version] => 0.9
    [majorver] => 0
    [minorver] => 9
    [cssversion] => 2
    [frames] => 1
    [iframes] => 1
    [tables] => 1
    [cookies] => 1
    [backgroundsounds] =>
    [vbscript] =>
    [javascript] => 1
    [javaapplets] => 1
    [activexcontrols] =>
    [cdf] =>
    [aol] =>
    [beta] => 1
    [win16] =>
    [crawler] =>
    [stripper] =>
    [wap] =>
    [netclr] =>
)

$browser = new BrowserDetection();
echo 'You are using ', $browser->getBrowser(), ' version ', $browser->getVersion();

$browser = new BrowserDetection();
if ($browser->getBrowser() == BrowserDetection::BROWSER_FIREFOX && $browser->compareVersions($browser->getVersion(), '5.0.1') !== 1) {
    echo 'You have FireFox version 5.0.1 or greater. ';
}

from flask import request

request.headers.get('User-Agent')

var os = (function() {
    var ua = navigator.userAgent.toLowerCase();
    return {
        isWin2K: /windows nt 5.0/.test(ua),
        isXP: /windows nt 5.1/.test(ua),
        isVista: /windows nt 6.0/.test(ua),
        isWin7: /windows nt 6.1/.test(ua),
        isWin8: /windows nt 6.2/.test(ua),
        isWin81: /windows nt 6.3/.test(ua)
    };
}());

if(os.isWin7) {
    ...
}