Simo Ahava's blog

One of the prime things to use Google Tag Manager for is script injection. Loading a third-party JavaScript library is trivial to do with a Custom HTML tag, and works like a charm. However, using Custom HTML tags for, well, anything, is no longer the preferred way to add custom code to the site. Custom HTML tags are pretty expensive DOM injections, and they can be incredibly dangerous tools (for UX, security, and privacy) in the wrong and/or inexperienced hands. Read More…

My latest custom tag template tackles a use case I've referred to a number of times before, especially in my article on sending weather data to Google Analytics. The problem is two-fold: How to fetch the user's IP address into dataLayer How to get latitude and longitude (as well as other geographical) data into dataLayer For this purpose, I've created a new Google Tag Manager custom tag template that leverages the IP Geolocation API service. Read More…

If you've opened the browser console in Google Chrome (since Chrome 76), you might have seen a bunch of warnings in a yellow background related to something called a SameSite cookie attribute that is either missing or incompletely set for cookies set on external domains. If you use Google Tag Manager, especially in Preview mode, you might have seen a warning about the http(s)://www.googletagmanager.com domain. Even though the warning is very prominent, hogging up some prime real estate in the browser console warning, it is, for now, just a warning. Read More…

Universal Analytics utilizes two components (by default) to attribute a browser session to a specific campaign: query parameters in the URL and the referrer string. The page URL is sent with every hit to Google Analytics using the Document location field, which also translates to the &dl parameter in the Measurement Protocol. The referrer string is sent with a hit to Google Analytics using the Document referrer field, as long as the referrer hostname does not exactly match that of the current page and the referrer string is not empty. Read More…

Google Tag Manager now lets you add unit tests directly to your custom templates. This is useful, since it allows you to control the code stability of your templates, especially if you've decided to share those templates with the public. I recently shared a general guide for how template tests work, but I wanted to expand the topic a little, and share with you two walkthroughs of custom template tests: one for a variable template and one for a tag template. Read More…

Google Tag Manager introduced the capability to add tests to your Custom Templates. Tests, in this context, refer specifically to unit tests that you write in order to make sure your template code works in a predictable way. Unit tests are also used to drive development, ensuring that you have added contingencies for all the different scenarios that the template, when coupled with user input, might introduce. In this guide, I'll introduce how the Tests feature works. Read More…

In Google Analytics: App + Web, you collect events. One event differs from another event by the name it uses. An event with the name page_view is different from, say, an event with the name file_download. This is all run-of-the-mill stuff. You know this. However, the fundamental change that App + Web introduces, when compared to Universal Analytics, is how event parameters are collected and processed. This gets more complicated than it should be. Read More…

There are lots of different readability formulas out there, which seek to provide an index on how readable any given excerpt of text is. Typically, these formulas output a grade-level score, which indicates, roughly, the level of education required to read the text excerpt with ease. Any “quality index” that seeks to reduce the complexity of something as multi-faceted as reading should be subject to scrutiny. This is true for Bounce Rate, this is true for Time On Page, and this is true for a readability score. Read More…

I've written about outbound link click tracking before. It's a very solid way to track interactions on the site, as clicking a link that leads away from a site is a signal of … well, something. In Google Tag Manager it's now extremely easy and efficient to track outbound link clicks, thanks to the introduction of a new configuration in the Auto-Event variable. This article will introduce the new method and show you how you can quickly set it up! Read More…

When previewing Custom HTML tags in Google Tag Manager you've almost certainly run into a situation where the GTM variable shows up as a weird JavaScript method resembling something like this: google_tag_manager["GTM-ABCD123"].macro(15) And this is when you were expecting it to show the actual, resolved value! It doesn't help that every now and then the preview mode actually shows to correct value in the preview mode. What's up with that? Well, there's a fairly logical explanation to this. Read More…