How to determine if Firefox is using privat browsing mode

Question

I would like all clients in the corporate network use private/incognito mode of a browser and alert them when they don't. I found solution for Chrome but I can't find the same for Firefox. Is it possible to achieve the same in Firefox using javascript?

Answer 1

Here's something you might find useful:

https://gist.github.com/cou929/7973956

For firefox, it checks against this:

window.indexedDB.open('test');
IDBOpenDBRequest { onblocked: null, onupgradeneeded: null, source: null, transaction: null, readyState: "pending", onsuccess: null, onerror: null, ownerGlobal: Window → about:privatebrowsing }

Answer 2

The simple answer is not reliably.

Depending on the OS and version of a browser, some hacks will work while others will not. This can result in 10, 20 or even more hacks to create and maintain for all the combinations of OS/browsers. It will be an ENORMOUS headache and it will still be unreliable.

Your best bet is to force your enterprise employees to use only one browser and do a custom build of it to force your settings. Here is how you can do it in Firefox. Otherwise, you won't have a reliable way to do this.

Good luck!