One of the difficulties of working with Google Tag Manager and the dataLayer structure is that GTM doesn’t preserve history of the items collected into its data model. Or, at least, it doesn’t preserve it in a manner that would let us access it. This is typically a very niche problem, but it does surface every now and then. For example, say you wanted to query whether an event with some specific value has already been pushed into dataLayer.
While using the Google Tag Manager user interface around Halloween 2018, you might have noticed a new tab in Google Tag Manager’s Preview mode. The tab is named Errors and shows you the number of exceptions thrown by GTM’s tag templates on the page. In this short #GTMTips post, I’ll quickly walk you through what the tab shows. Tip 90: The Errors Tab In Preview Mode The tab’s name is an apt description of what the tab shows.
Google Tag Manager offers us some nice built-in triggers so that we can automatically listen for specific user interactions on the website, reacting to them however we wish, though typically it would be to fire a tag. The tricky thing especially with the click triggers and form submission tracking is that the page has a nasty habit of redirecting you to the link or form target page before letting you see the respective data in Google Tag Manager’s excellent preview mode.
One of the coolest features of Google Analytics and, as a consequence, Google Tag Manager is customTask. It’s a method you can use to add and execute code as the hit to Google Analytics is being generated. I’ve written A LOT about customTask, and much of the feedback I’ve received has been around the question of how to combine all these different tricks into one customTask script. The problem is, you see, that a tag or hit can only have one customTask script attached to it, so the code within must combine all the different tricks I’ve been writing about over the past months.
Getting cross-domain tracking right in Google Analytics is difficult. Even if you use Google Tag Manager. There are many known issues when cross-domain tracking iframes, for example. Google Tag Manager implements the cross-domain tracking plugin quite handily via the Universal Analytics tag template, and often the easiest way to track links and form submits is to use the Auto-Link Domains option, as described in this great series of posts on cross-domain tracking by Bounteous.
One of the more difficult concepts in Google Tag Manager is the data model. In essence, the data model is what Google Tag Manager uses to populate the Data Layer variable. You might be tempted to think that it’s the same thing as the dataLayer array, but it’s not. The data model is a representation of the keys and values you push into dataLayer. Whenever you push any key into dataLayer, GTM grabs this key and updates the corresponding key in its data model with the new value, or in the case of objects and arrays merges the old and the new value together.