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Detect private browsing mode (InPrivate Browsing or Incognito).
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);
}
);
}
<!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>
@thelinuxlich

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commented Oct 21, 2014

Fantastic! It works!

@AndreSchwarzer

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commented Jan 21, 2015

Doesn't work in chrome :(

@apastuhov

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commented Jun 1, 2015

I tried to test in Chrome and IE 11. Your script return "private" even when it is not private.

@alexesDev

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commented Aug 25, 2015

Eslint check...

   2:41  error  interval is defined but never used    no-unused-vars
  40:15  error  e is defined but never used           no-unused-vars
  90:16  error  is_timeout is defined but never used  no-unused-vars
@yukulele

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commented Jan 5, 2016

how it works?

@chickenwing

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commented Feb 7, 2016

hmm, could this be expanded to work in the edge browser?

@sundip111

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commented Apr 5, 2016

Awesome, works in all major browsers on both desktop and mobile.

Modify "isIE10OrLater" function as following for it to work with Edge browser:

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; } var edge = /edge/.exec(ua); if(edge && edge[0] == "edge"){ return true; } return false; }

@jimmywarting

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commented May 5, 2016

Is userAgent sniffing good? how about:

var isSafari = /constructor/i.test(window.HTMLElement);
var isFF = 'MozAppearance' in document.documentElement.style;
var isIE10OrLater = document.body.style.msTouchAction !== undefined;

From: http://browserhacks.com
Btw, i ended up with 1/4 of that code using other methods: https://jsfiddle.net/Lj2fs5kr/
tested in latest Chrome, FF, Safari everything is good there. Don't have IE on Mac
I think you are overusing try/catch more then necessary...?

Also found something about InPrivateFilteringEnabled in IE, maybe that could be to any use?
Update: tried InPrivateFilteringEnabled in edge 13, didn't work

@radyk

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commented Jun 1, 2016

https://jsfiddle.net/Lj2fs5kr/

How do I use this above to test at the appropriate point in my forum. I need something like this as a test but I have no idea how to actually use this code in the real world. I can determine where to test but not how to call this code.

@slonoed

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commented Jun 30, 2016

This line in FF incognito raise InvalidStateError
https://gist.github.com/cou929/7973956#file-detect-private-browsing-js-L48
It looks like error happened in different thread. How catch it?

@dev0x10

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commented Oct 3, 2016

@charltoons

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commented Jan 13, 2017

@slonoed You can catch the error by returning true in onerror. That one took me a few hours.

@kylestev

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commented Jan 14, 2017

@charltoons Glad I saw your comment! Thanks for saving me a few hours 😜

@jonathanlermitage

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commented Feb 22, 2017

Doesn't work if you use uBlock Origin :)

@bkstorm

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commented Mar 28, 2017

It works well with Chrome, Firefox and Safari. Good job 👍

@Vamshidharredy

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commented Mar 29, 2017

Broken for the latest Chrome. Chrome 57.

@Vadimgorlenko

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commented Apr 12, 2017

Works fine for me in latest Chrome and FF (Win 10), but does not work in Edge

@lucasrodriguex

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commented Apr 24, 2017

Doesn't work with Chrome version 57+

@cesky84

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commented Apr 27, 2017

Doesn't work with FF 53 on mac return only private result

@rohankhudedev

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commented Jun 21, 2017

i did testing on some latest browser versions

Working-

Firefox - 54(latest), 53
Chrome - 58(latest)
Safari - 6.0.2, 5.1
IE - 11, 10
Opera - 45(latest)

Not working on -

UC browser - 11.3(latest)

@PunKeel

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commented Jul 8, 2017

Safari throws an error when cookies are disabled globally (private mode or not) because it also breaks the localStorage.
The script aborts, and callback is never called :-(

> window.localStorage; console.log("hello");
< SecurityError (DOM Exception 18): The operation is insecure.

The fix: use a try-catch to interact with the localStorage

Bonus (thanks to @jherax): use navigator.cookieEnabled to detect if cookies are enabled. cf https://gist.github.com/jherax/a81c8c132d09cc354a0e2cb911841ff1

My fix, which might not work in every cases (but works fine for me): check if cookies are enabled before checking if localStorage is available:

- } else if (window.localStorage && /Safari/.test(window.navigator.userAgent)) {
+ } else if (/Safari/.test(window.navigator.userAgent) && navigator.cookieEnabled && window.localStorage) {
@BlueCutOfficial

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commented Jul 25, 2017

Microsoft Edge passes the case for Safari.
Add this at the top of Safari case block :

 if (!window.indexedDB && (window.PointerEvent || window.MSPointerEvent)) {
  is_private = true;
}

No problem for Firefox / Chrome / Safari, nice job ! :)

@JessicaYeh

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commented Aug 16, 2017

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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commented Sep 13, 2017

IE and Mozilla is returning private, but its not.

@Maykonn

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commented Sep 27, 2017

@JessicaYeh on desktop version 11 not works more too.

@Maykonn

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commented Oct 6, 2017

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

@Maykonn

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commented Oct 6, 2017

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

@forberg

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commented Oct 6, 2017

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

@jdc20181

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commented Oct 15, 2017

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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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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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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commented Nov 29, 2017

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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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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commented Dec 15, 2017

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

@yimaneilicj

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commented Dec 15, 2017

@ckimy This code does not work in ios10 above

@dkuryakin

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commented Dec 19, 2017

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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commented Dec 21, 2017

@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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commented Jan 11, 2018

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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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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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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commented May 7, 2018

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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commented May 8, 2018

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

@Maykonn

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commented Jul 20, 2018

@tormod17

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commented Nov 6, 2018

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

@gremz

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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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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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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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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!

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