Tag Manager: Fire Tag Only if CSS Class is Absent
I finally stepped away from Google Analytics and implemented Plausible's cookie-free tracking on the blog. Ironically, to implement Plausible's code, I used Google's Tag Manager (this doesn't compromise Plausible's code in any way; I just think it's sad that Google is still a crutch for my dev-ops). Since Plausible doesn't gather Personally Identifiable Information (PII), though, excluding my own usage on the site becomes a slight challenge; Google Analytics let's you exclude data based on IP--but, that's not an option with Plausible. With the help of Tag Manager, however, I can prevent Plausible's code from loading based on whether a CSS class is present on a DOM Element. When logged into Drupal, there are any number of CSS classes that are unique in the DOM. This provides a simple solution to excluding my own usage from Plausible's analytic data. Here's how to do that.
Step 1: Finding Unique Classes in the DOM
This technique isn't limited to excluding analytics tags. By finding unique classes in the DOM, you can setup both exclusion and inclusion rules for Tag Manager to fire a tag of any type. This is actually a pretty powerful ability. In my case, though, I need to find a CSS class (or classes) in the DOM that only appears when I'm logged into the blog. Drupal adds these kinds of classes throughout the DOM, but the most logical candidate, for me, is a class in the <body> tag.