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cou929/detect-private-browsing.js

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Detect private browsing mode (InPrivate Browsing or Incognito).
Raw
detect-private-browsing.js
function retry(isDone, next) {
var current_trial = 0, max_retry = 50, interval = 10, is_timeout = false;
var id = window.setInterval(
function() {
if (isDone()) {
window.clearInterval(id);
next(is_timeout);
}
if (current_trial++ > max_retry) {
window.clearInterval(id);
is_timeout = true;
next(is_timeout);
}
},
10
);
}
function isIE10OrLater(user_agent) {
var ua = user_agent.toLowerCase();
if (ua.indexOf('msie') === 0 && ua.indexOf('trident') === 0) {
return false;
}
var match = /(?:msie|rv:)\s?([\d\.]+)/.exec(ua);
if (match && parseInt(match[1], 10) >= 10) {
return true;
}
return false;
}
function detectPrivateMode(callback) {
var is_private;
if (window.webkitRequestFileSystem) {
window.webkitRequestFileSystem(
window.TEMPORARY, 1,
function() {
is_private = false;
},
function(e) {
console.log(e);
is_private = true;
}
);
} else if (window.indexedDB && /Firefox/.test(window.navigator.userAgent)) {
var db;
try {
db = window.indexedDB.open('test');
} catch(e) {
is_private = true;
}
if (typeof is_private === 'undefined') {
retry(
function isDone() {
return db.readyState === 'done' ? true : false;
},
function next(is_timeout) {
if (!is_timeout) {
is_private = db.result ? false : true;
}
}
);
}
} else if (isIE10OrLater(window.navigator.userAgent)) {
is_private = false;
try {
if (!window.indexedDB) {
is_private = true;
}
} catch (e) {
is_private = true;
}
} else if (window.localStorage && /Safari/.test(window.navigator.userAgent)) {
try {
window.localStorage.setItem('test', 1);
} catch(e) {
is_private = true;
}
if (typeof is_private === 'undefined') {
is_private = false;
window.localStorage.removeItem('test');
}
}
retry(
function isDone() {
return typeof is_private !== 'undefined' ? true : false;
},
function next(is_timeout) {
callback(is_private);
}
);
}
Raw
example.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<div id="result"></div>
<script src="detect-private-browsing.js"></script>
<script>
detectPrivateMode(
function(is_private) {
document.getElementById('result').innerHTML = typeof is_private === 'undefined' ? 'cannot detect' : is_private ? 'private' : 'not private';
}
);
</script>
</body>
</html>
@JessicaYeh
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On iOS 11 Safari (and probably the new version of desktop Safari too? but didn't check that one), that trick of seeing if window.localStorage.setItem('test', 1); throws an error no longer works, because it no longer throws an error, and it also properly sets the localStorage item. Has anyone figured out any other way to check for private browsing mode in the new versions of Safari?

@N1CHTN3BIH
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IE and Mozilla is returning private, but its not.

@Maykonn
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Maykonn commented Sep 27, 2017

@JessicaYeh on desktop version 11 not works more too.

@Maykonn
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Maykonn commented Oct 6, 2017 •
edited

On Firefox ESR 53.0 not working. The script always returns as private.

@Maykonn
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Maykonn commented Oct 6, 2017

I asked a question on Stackoverflow with more details about Firefox specific errors, here.

@forberg
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forberg commented Oct 6, 2017 •
edited

@Maykonn Seems like navigator.doNotTrack is not null in Safari private mode on iOS

@jdc20181
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Seems to be giving a false "Not private" - Meaning it should say private but it isn't - Using GeckFX (FireFox) .NET Control, I have the appropriate configurations for private mode, I just don't think its compatible with FF- Information on what I am using: https://bitbucket.org/geckofx/geckofx-45.0/issues/94/private-browsing

Not sure if its a JS issue or its something with the control/engine itself. My guess is it has something to do with the JS, with how it is detecting it via the code - or the version fo the engine itself although that should be ok.

@Maykonn
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Maykonn commented Oct 24, 2017

I'm testing in various FF versions and from version 52 below don't working. Always returning as private browsing.
Safari latest version don't working too. I'm making tests with navigator.doNotTrack @forberg, thanks.

@mtage70
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mtage70 commented Oct 27, 2017

navigator.doNotTrack is just a Safari feature that asks sites not to track the user, it can be opted into by going to safari->preferences->privacy. navigator.doNotTrack is not null if the user has checked that option, it is not indicative of whether the user is in private mode or not.
I'm still investigating how to detect private browsing in Safari, if anyone else is interested in this feature we should join forces

@unlox775
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unlox775 commented Nov 29, 2017 •
edited

Note: this does not seem to detect private browsing for iOS 11 Safari. It detects find in iOS 10 and 9 Safari.

@ckimy
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ckimy commented Nov 30, 2017

Guys I found a solution.
You can detect private browsing in iOS 11 using below code. 😄
No matter user's DNT option is checked or not, you can detect private browsing mode properly.

var isPrivate = false;
try {
   window.openDatabase(null, null, null, null);
} catch (_) {
   isPrivate = true;
}
alert((isPrivate ? 'You\'re' : 'You aren\'t')  + ' in private browsing mode');

It worked for me perfectly. If it doesn't, please let me know.

@yimaneilicj
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@ckimy Think you very much! Let's dance!

@yimaneilicj
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@ckimy This code does not work in ios10 above

@dkuryakin
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dkuryakin commented Dec 19, 2017 •
edited

Hey, guys! There is my own version of snippet, based on original gist and some comments.
Check this out: https://jsfiddle.net/n0hnu5te/1/

It works for me in:

  • IE11
  • Chrome 63.0
  • Mobile Chrome 62.0 (Android)

Let's test it on different devices/oses/browsers!

@ckimy
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ckimy commented Dec 21, 2017 •
edited

@yimaneilicj Of course, this snippet is only for ios11. You can combine this snippet with another library/modules for other browsers. @dkuryakin had done this job for us! :)

@smarajitdasgupta
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smarajitdasgupta commented Jan 11, 2018 •
edited

Does anyone have a snippet that detects private mode on Safari on iOS11 as well as older Safari?

Update: Here is a pen that attempts to combine the storage and openDatabase try-catch blocks.
https://codepen.io/anon/pen/zpMZjp

The test window.openDatabase(null, null, null, null)
is not expected to throw an exception in Safari non-private browser mode, but it does (exception code 18).

In Safari new versions (11+ or iOS11+ Safari) normal browser mode, the second test (for openDatabase) enters the catch and isPrivate gets set to true. So, in Safari 11+ non-private mode is also detected as private mode. Anyone with a working solution on a server? It seems to work as expected in localhost, but window.openDatabase(null, null, null, null) throws exception both in normal and private mode when hosted in some server, as can be seen in the pen.

@gaplyk
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gaplyk commented Mar 8, 2018

IE can return true when it's not when you have your restriction on your policy to disable indexedDB

@mtage70
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mtage70 commented Apr 17, 2018

I've noticed in Safari 11 normal browsing mode window.openDatabase(null, null, null, null) will throw an exception if a user has just cleared their history and refreshed.

@bigmike7801
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I'm using Safari 11.1 (11605.1.33.1.4) on OSX 10.11.6 and am getting "not private" when using a private window.

@bigmike7801
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bigmike7801 commented May 8, 2018 •
edited

I switched line 82 to "true" and that seemed to fix it for me.

@Maykonn
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Maykonn commented Jul 20, 2018 •
edited

@tormod17
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tormod17 commented Nov 6, 2018

Has anyone found a solution for chrome IOS 12 + for detecting private mode?

@gremz
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gremz commented Nov 16, 2018

@tormod17 where/how are you trying to attempting this check? Any chance you're doing this in an iframe?

@gu10214
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gu10214 commented Feb 8, 2019

False positive on iOS 12+ as tormod17 mentioned, are we playing whack a mole here with each iOS release/patch?

@narcisso
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narcisso commented Apr 2, 2019 

function isPrivate(callback) {
  callback || (callback = function(){});
  var fs = window.RequestFileSystem || window.webkitRequestFileSystem;

  if(fs){
    return fs(window.TEMPORARY, 1, callback.bind(this, false), callback.bind(this, true));
  }

  if(window.indexedDB && /Firefox/.test(window.navigator.userAgent)){
    try {
      var db       = window.indexedDB.open('test');
      var tryes    = 0;
      var interval = limit = 10;

      var wait = function(check){
        if(tryes >= limit){ return callback(true); } // Give up
        return window.setTimeout(check, ++tryes * interval);
      }

      var evaluate = function(){
        return db.readyState === 'done' ? callback(!db.result) : wait(evaluate);
      }

      return wait(evaluate);
    } catch (e) {
      return callback(true);
    }
  }

  if (!!window.navigator.userAgent.match(/(MSIE|Trident|Edge)/)){
    try {
      return callback(!window.indexedDB);
    } catch (e) {
      return callback(true);
    }
  }

  try {
    window.openDatabase(null, null, null, null);
    return callback(false);
  } catch (e) {
    return callback(true);
  }
}

isPrivate( function(isPrivate) {
  console.log('Private mode ===>', isPrivate);
});

@0c0c0f
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0c0c0f commented May 13, 2019 

function isPrivate(callback) {
  callback || (callback = function(){});
  var fs = window.RequestFileSystem || window.webkitRequestFileSystem;

  if(fs){
    return fs(window.TEMPORARY, 1, callback.bind(this, false), callback.bind(this, true));
  }

  if(window.indexedDB && /Firefox/.test(window.navigator.userAgent)){
    try {
      var db       = window.indexedDB.open('test');
      var tryes    = 0;
      var interval = limit = 10;

      var wait = function(check){
        if(tryes >= limit){ return callback(true); } // Give up
        return window.setTimeout(check, ++tryes * interval);
      }

      var evaluate = function(){
        return db.readyState === 'done' ? callback(!db.result) : wait(evaluate);
      }

      return wait(evaluate);
    } catch (e) {
      return callback(true);
    }
  }

  if (!!window.navigator.userAgent.match(/(MSIE|Trident|Edge)/)){
    try {
      return callback(!window.indexedDB);
    } catch (e) {
      return callback(true);
    }
  }

  try {
    window.openDatabase(null, null, null, null);
    return callback(false);
  } catch (e) {
    return callback(true);
  }
}

isPrivate( function(isPrivate) {
  console.log('Private mode ===>', isPrivate);
});

window chrome the result is error!

@aneudy1702
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aneudy1702 commented Mar 26, 2020 •
edited

This does not seem to work anymore

https://twitter.com/paul_irish/status/1138471166115368960

for desktop you can use

https://mishravikas.com/articles/2019-07/bypassing-anti-incognito-detection-google-chrome.html

(async () => {
  if ("storage" in navigator && "estimate" in navigator.storage) {
    const { usage, quota } = await navigator.storage.estimate();
    console.log(`Using ${usage} out of ${quota} bytes.`);
    if (quota < 120000000) {
      console.log("Incognito");
    } else {
      console.log("Not Incognito");
    }
  } else {
    console.log("Can not detect");
  }
})();

@esemeniuc
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Incorrect reading for Chrome 81 when not in incognito

@mritgupta
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mritgupta commented Sep 14, 2020 •
edited

It's able to detect private mode in chrome 85

@kuldeepchopradotnet
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not working with latest version

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