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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>
@ckimy

ckimy commented Nov 30, 2017

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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

yimaneilicj commented Dec 15, 2017

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

@yimaneilicj

yimaneilicj commented Dec 15, 2017

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@ckimy This code does not work in ios10 above

@dkuryakin

dkuryakin commented Dec 19, 2017 •
edited
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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

ckimy commented Dec 21, 2017 •
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@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

smarajitdasgupta commented Jan 11, 2018 •
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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

gaplyk commented Mar 8, 2018

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

@mtage70

mtage70 commented Apr 17, 2018

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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

bigmike7801 commented May 7, 2018

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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

bigmike7801 commented May 8, 2018 •
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I switched line 82 to "true" and that seemed to fix it for me.

@Maykonn

Maykonn commented Jul 20, 2018 •
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@tormod17

tormod17 commented Nov 6, 2018

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

@gremz

gremz commented Nov 16, 2018

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

@gu10214

gu10214 commented Feb 8, 2019

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

@narcisso

narcisso commented Apr 2, 2019

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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

0c0c0f commented May 13, 2019

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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

aneudy1702 commented Mar 26, 2020 •
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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

esemeniuc commented Apr 16, 2020

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Incorrect reading for Chrome 81 when not in incognito

@mritgupta

mritgupta commented Sep 14, 2020 •
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It's able to detect private mode in chrome 85

@kuldeepchopradotnet

kuldeepchopradotnet commented Mar 2, 2021

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not working with latest version

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