Javascript : How to check a browser's Do Not Track status?

Problem :

You work for an advertisement network and you want to respect a visitor's Do Not Track status. How to detect or check if a visitor's browser Do Not Track is turn on or off?

Solution :

Use Javascript to extract the doNotTrack variable from the browser.

• Chrome and Firefox based browser use navigator.doNotTrack
• Safari is window.doNotTrack and
• Microsoft Internet Explorer use navigator.msDoNotTrack

The value returned is usually yes or 1.

For example, to check Do Not Track status for most common browsers

 var DNT = window.doNotTrack == "1" || navigator.doNotTrack == "yes" || navigator.doNotTrack == "1" || navigator.msDoNotTrack == "1";

or

 console.log(navigator.doNotTrack); 

IF DNT is true, then the browser's Do Not Track is turned ON. If false or unspecified, then OFF.

[This solution will only work properly if Javascript is turned on.]

NOTE :

At the moment of writing, most ads networks will not honor Do Not Track status. Browser based add-on like Privacy Badger will be able to tell you which trackers will honor or ignore the Do Not Track status. In the long run, it will be wise to respect a visitor's decision to turn on Do Not Track.

Special thanks to Mr. Джон Сора of Russia for introducing Privacy Badger to me.

References :

http://donottrack.us/

https://developer.mozilla.org/en-US/docs/Web/API/navigator/doNotTrack