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Javascript Navigator Tutorial

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1- window.navigator

The window.navigator object contains information on user's browser, for example, browser name, version, .... You can access the navigator object without using the window prefix. 
  • navigator.appName
  • navigator.appCodeName
  • navigator.platform
  • ...

2- navigator.product

navigator.product always returns "Gecko" for all browsers

var prodName = navigator.product; // Gecko

3- navigator.appName

navigator.appName returns the browser application name. But in fact it doesn't make much sense because in most cases it returns "Netscape", specifically, to different browsers: 
  • IE11+, Firefox, Chrome and Safari returns "Netscape".
  • IE 10 and earlier versions return "Microsoft Internet Explorer".
  • Opera returns "Opera".

var appName = navigator.appName;
 

4- navigator.appCodeName

navigator.appCodeName returns the browser code name. But it doesn't make much sense because all browsers return the "Mozilla" value, which implies that this browser is compatible with Mozilla

var codeName = navigator.appCodeName; // Mozilla

5- navigator.appVersion

navigator.appVersion returns browser version information.
appVersion-example.html
<!DOCTYPE html>
<html>
   <head>
      <title>Navigator appVersion</title>
      <meta charset="UTF-8">
      <style>textarea {width:100%;margin-top:10px;}</style>
   </head>
   <body>

       <h1>navigator.appVersion</h1>

       <button onClick="showInfos()">Show Infos</button>

        <textarea name="name" rows="5" id="log-area"></textarea>

        <script>
           function showInfos()  {

             var logArea = document.getElementById("log-area");
             logArea.value = navigator.appVersion;
           }
           showInfos();
        </script>
   </body>
</html>
 
Run the example on the Chrome (Windows 7) browser and receive the result:
Run the example on Firefox (Windows 7) browser and receive the result:

6- navigator.platform

navigator.platform returns platform name on which the browser is compiled. It can return a empty string if the browser refuses or cannot identify the platform. Values can be:
  • HP-UX
  • Linux i686
  • Linux armv7l
  • Mac68K
  • MacPPC
  • MacIntel
  • SunOS
  • Win16
  • Win32
  • WinCE
  • Etc..
Most browsers, including Chrome, Edge, and Firefox 63 and later, return "Win32" even if running on a 64-bit version of Windows, Internet Explorer and versions of Firefox prior to version 63 still report "Win64".

7- navigator.cookieEnabled

navigator.cookieEnabled returns true if the browser enables Cookie, vice versa, return false.
Configure Chrome browser to turn on or turn off  Cookie:
Configure Firefox browser to turn on or turn off ​​​​​​​Cookie:
See Also:

8- navigator.geolocation

navigator.geolocation returns a Geolocation object, containing user's position information such as longitude, latitude,... .This allows a website or application to offer customized results based on the user's location
Note: For security reasons, when a web page tries to access location information, the user is notified and asked to grant permission. Be aware that each browser has its own policies and methods for requesting this permission.
Example:
geolocation-example.js
// Success Handler
function successHandler(position)  {
  var logArea = document.getElementById("log-area");

  logArea.value = "";
  logArea.value += "Latitude: " + position.coords.latitude + "\n";
  logArea.value += "Longitude: " + position.coords.longitude + "\n";
}

// Error Handler
function errorHandler(positionError)  {
   if(positionError.code == PositionError.PERMISSION_DENIED) {
       alert("Error: Permission Denied!");
   } else if(positionError.code == PositionError.POSITION_UNAVAILABLE) {
       alert("Error: Position Unavailable!");
   } else if(positionError.code == PositionError.TIMEOUT) {
       alert("Error: Timeout!");
   }
}

function showInfos()  {
  navigator.geolocation.getCurrentPosition(successHandler, errorHandler);
}

 
geolocation-example.html
<!DOCTYPE html>
<html>
   <head>
      <title>Navigator geolocation</title>
      <meta charset="UTF-8">
      <style>textarea {width:100%;margin-top:10px;}</style>

      <script src="geolocation-example.js"></script>
   </head>
   <body>

       <h1>navigator.geolocation</h1>

       <button onClick="showInfos()">Show Infos</button>

        <textarea name="name" rows="5" id="log-area"></textarea>
   </body>
</html>

 
Geolocation is a pretty large API, so it needs to be introduced in a separate post. If you are interested, you can see the following post:

9- navigator.language

navigator.language returns a string representing the user's preferred language, also known as the "Browser UI"  language.

var lang = navigator.language
 
Values can be "en", "en-US", "fr", "fr-FR", "es-ES", ... It is noted that the Safari browser on MacOS and iOS before version 10.2, country code is lowercase "en-us", "fr-fr", "es-es", ...

10- navigator.onLine

navigator.onLine returns the online status of the browser. It returns true, that is, the browser is onlineon the contrary, it returns false. Its value is updated when a user accesses a link or a request is sent to the server by JavaScript.

var online = navigator.onLine;
Different browsers may have slightly different online concepts. 
In Chrome and Safari, If a browser cannot connect to a local area network (LAN) or Router, it will be offline, on the contrary,  it is considered online. This means that your getting true value does not mean that you can access the Internet.
There are some situations causing you to make false judgments. For example, your computer is installed a Virtual Network. If this virtual network is always connected, navigator.onLine will return true value. Therefore, if you really want to determine browser's online status, you need to develop additional means to test. To learn more you can refer to the following post:
In Firefox (version <= 41), Internet Explorer if you change the mode of browser to offline status, navigator.onLine returns false value; on the contrary, it always returns true. For Firefox (version > 41) act is the same as Chrome and Safari.
You can see changes in network status by listening to events on  window.ononline and window.onoffline.
onLine-example.html
<!DOCTYPE html>
<html>
   <head>
      <title>Navigator onLine</title>
      <meta charset="UTF-8">

      <style>textarea {width:100%;margin-top:10px;}</style>

      <script>
        function updateOnlineStatus(msg) {
            var logArea = document.getElementById("log-area");

            logArea.value += msg +"\n";
            logArea.value += "navigator.onLine = " + navigator.onLine +"\n";
            logArea.value += "---------------------\n";
        }

        function loaded() {
            updateOnlineStatus("Load Event");

            document.body.addEventListener("offline", function () {
                updateOnlineStatus("Offline Event")
            }, false);

            document.body.addEventListener("online", function () {
                updateOnlineStatus("Online Event")
            }, false);
        }
      </script>

   </head>
   <body onload = "loaded()">

       <h1>navigator.onLine</h1>

      <textarea rows="8" id="log-area"></textarea>

   </body>
</html>
 

11- navigator.userAgent

Everywhen a browser sends a request to a server, it attaches a piece of information on Header which is user-agent. The User Agent provides the server a short information on the user's browser and operating system. 

var userAgent = navigator.userAgent;
General structure of the User Agent string:
appCodeName/appVersion number (Platform; Security; OS-or-CPU; 
Localization; rv: revision-version-number) product/productSub 
Application-Name Application-Name-version
For example, this is User Agent string sent to the server from the Firefox browser which is running on the Windows 7 operating system:
Firefox/Windows 7
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20100101 Firefox/12.0
The User Agent of the Internet Explorer 9 browser runs on the Windows 7 operating system:
IE9/Windows 7
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)
The User Agent string of the Chrome browser runs on the Windows 7 operating system:
Chrome/Windows 7
Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36
You also can visit the following address to view the User Agent of your browser:
Browser identification based on the detection of the User Agent string is unreliable and not encouraged because users can customize it. Example: 
  • For Firefox browser, you can customize User Agent by amending general.useragent.override in about:config.
  • For Opera 6+ you can set browser identification string through Menu.
  • For Internet Explorer you can change User Agent via Windows Registry.
  • ....
Using JavaScript, you also can customize the User Agent given to server.
JavaScript

navigator.__defineGetter__('userAgent', function() {
    return "Mozilla/5.0 (Windows NT 6.2; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0)"
});
jQuery
$.ajaxSetup({
    beforeSend: function(request) {
        request.setRequestHeader("User-Agent",
             "Mozilla/5.0 (Windows NT 6.2; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0)");
    }
});

12- navigator.javaEnabled()

navigator.javaEnabled() returns true value, that means this browser enables to allow Java applications to operate, for example, Java Applet. You can enable or disable it through browser options.
Basically when the browser finds out that a Java application prepares to be run, it will request a permission from a user.

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