One of Google Tag Manager’s oldest and most reliable features is that it freezes the state of Data Layer variables to the moment when the trigger event occurred. Thus, any tags firing on this trigger (and any variables resolved on this trigger event) will always have access to the same value of each Data Layer variable. However, there are situations where this is not a good thing. One is tag sequencing, and the other is a scenario where you want to run some custom code that should access the latest value of the Data Layer variable at a moment in time after the tag has already fired.

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Every now and then I’m fortunate enough to be able to publish guest posts by illustrious people in the analytics and digital marketing industries. This time, I get to work with an old colleague of mine who’s a veritable wizard when it comes to building solutions that make our daily work in the digital industry so much smoother. Erik Grönroos works as an analyst in MarkkinointiAkatemia, a Finnish digital customer acquisition agency.

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Some four years ago, Google Tag Manager released a new trigger predicate named matches CSS selector. Slowly but surely, it has evolved into one of the most useful little features in GTM. Even though I’ve written about CSS selectors many times before, I wanted to compile all the relevant information into a single guide. For an external resource, I recommend bookmarking the w3schools.com CSS Selector Reference. But for your day-to-day use of CSS selectors in GTM, this guide will hopefully prove useful.

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Trigger Group is the newest trigger type you can add to a tag in Google Tag Manager. It allows you to establish dependencies between multiple triggers, not firing the tag until every trigger in the group has fired at least once. This establishes an interesting new paradigm in Google Tag Manager, because until now it wasn’t possible to create triggers that relied on earlier values of a given key (event in this case).

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One of the myths surrounding Google Analytics is that the first hit of a session should always be a pageview. It makes sense - sessions are initialized with a landing page, and thus need a page view to have one. However, in this article I want to show you empirically how this myth is just that - a myth. There is little discernible impact if the first hit of a session is an event, and GA is more than capable of stitching the first event together with the subsequent pageview into a session entity.

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In Google Tag Manager, the Custom JavaScript variable is an anonymous function with a return statement. It does not take any parameters, and by default it’s impossible to pass any parameters to it, because the Custom JS variable is simply resolved to whatever value the function returns. If it returns a number, for example, passing a parameter to it would make no sense and would result in a TypeError since the variable resolves to a number, not a function.

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Updated 1 October 2019 With ITP 2.3 it looks like Safari is reducing the usefulness of localStorage as well, so using that as an alternative fix to persistence issues should not be considered future-proof. this solution should not be considered future-proof. Updated 12 March 2019 with some minor clarifications.. On 21st February 2019, WebKit announced the release of the latest iteration of Safari’s Intelligent Tracking Prevention (ITP), known as ITP 2.

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