Last night I released WP DoNotTrack version 0.7.0, which adds a new filtering mode called SuperClean. Whereas the previous version only acted on elements added to the DOM, SuperClean now also allows you to filter the base HTML of your pages. To do this, SuperClean uses the PHP output buffer to catch the full HTML before it’s being sent to the browser. That HTML is then parsed with PHP Simple HTML DOM Parser and based on your black- or whitelist the filtering is applied (SuperClean + whitelist = running a very tight ship, really). Currently SuperClean is not available if you have configured WP DoNotTrack to only stop tracking for people who have set the DoNotTrack-flag in their browser.
While we’re on the subject of conditional filtering; I’ve updated the code that checks for the DoNotTrack-flag to work around differences in browser implementations. Conditional filtering is pretty important, as it can help websites to comply with the (for now UK-only) “EU Cookie Law” which requires websites to ask their visitors for explicit consent prior to setting cookies. With WP DoNotTrack you can have your cookie and eat it too; you have your existing tracking scripts for users who give consent, while still being able to serve a “clean” website for users who enabled DoNotTrack in their browser. Given the fact that similar laws will be coming to a EU-country near you, conditional filtering is something I’ll be looking into further, so any feedback on the current implementation is more than welcome!