Detect “Do Not Track” with JavaScript

By  on  

Do Not Track is an excellent idea.  The DNT website describes it best:

Do Not Track is a technology and policy proposal that enables users to opt out of tracking by websites they do not visit, including analytics services, advertising networks, and social platforms. At present few of these third parties offer a reliable tracking opt out, and tools for blocking them are neither user-friendly nor comprehensive. Much like the popular Do Not Call registry, Do Not Track provides users with a single, simple, persistent choice to opt out of third-party web tracking.

The preference is sent from the client to the server via a HTTP header but you can also get its value using JavaScript:

// "1" or "unspecified"
if(navigator.doNotTrack == 1) {
    // Do (or don't do) stuff.
}

If you wanted to be extreme about honoring your user's preference, you could use that to lazyload (or not) advertising, analytics, or other utilities. Probably a bit extreme but it's there for you to use!

Recent Features

  • By
    CSS 3D Folding Animation

    Google Plus provides loads of inspiration for front-end developers, especially when it comes to the CSS and JavaScript wonders they create. Last year I duplicated their incredible PhotoStack effect with both MooTools and pure CSS; this time I'm going to duplicate...

  • By
    CSS Filters

    CSS filter support recently landed within WebKit nightlies. CSS filters provide a method for modifying the rendering of a basic DOM element, image, or video. CSS filters allow for blurring, warping, and modifying the color intensity of elements. Let's have...

Incredible Demos

  • By
    Do / Undo Functionality with MooTools

    We all know that do/undo functionality is a God send for word processing apps. I've used those terms so often that I think of JavaScript actions in terms of "do" an "undo." I've put together a proof of concept Do/Undo class with MooTools. The MooTools...

  • By
    Animated AJAX Record Deletion Using Dojo

    I'm a huge fan of WordPress' method of individual article deletion. You click the delete link, the menu item animates red, and the item disappears. Here's how to achieve that functionality with Dojo JavaScript. The PHP - Content & Header The following snippet goes at the...

Discussion

  1. Is the resulting value always a string or an integer except when unspecified (then it is a string), and are the values you stated the same cross-browser (especially the unspecified value)?

  2. Matt

    I really like how medium handles DNT.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!