Ever since Server-side tagging was publicly announced at SUPERWEEK 2020, Google and the trusted tester community have been hard at work, building something that just might change the landscape of digital analytics for good. Google Tag Manager has now released Server-side tagging into public beta. In this lengthy article, we’ll take a look at what Server-side tagging is, how it should (and should not) be used, and what its implications are on the broader digital analytics community.

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In this step-by-step guide, I’ll show you how to build a Lookup Table generator in Google Sheets, utilizing Apps Script and the Google Tag Manager API. The purpose of the Lookup Table generator is to automate the often tedious task of adding many, many rows to a Lookup Table within the Google Tag Manager UI. There are other solutions for this, but none (as far as I know) that uses the Google Tag Manager API.

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Since updating to Google Chrome 83, you might have noticed that Google Tag Manager’s Preview mode no longer works when browsing Chrome in Incognito mode. This is because starting with Chrome 83, third-party cookies are blocked by default in Incognito windows. Google Tag Manager uses third-party cookies to serve browsers in Preview mode with the container draft rather than the live container. There’s a simple workaround to make sure Preview mode continues working for any site you want to browse in Preview mode.

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Recently I published an article on how to set up an impact test for the “flicker effect” omnipresent in client-side A/B-testing tools. Be sure to check out that article first to get some context to what we’re going to be talking about here. In this short follow-up, I’ll show you how to measure the average time of the anti-flicker snippet delaying page visibility, if you choose to deploy the snippet.

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“Flickering” or “Flash Of Original Content” (FOOC) is a phenomenon where there’s a (typically) slight but observable delay in the browser updating the site or element layout if the user is included in a variant group for experimentation. This manifests in the original, unmodified element being rendered in the visible portion of the page before the experiment library updates it with the variant. There are ways to mitigate the flicker:

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When custom templates were released for Google Tag Manager, I updated my workflow for working with GTM. Instead of instinctively rushing to the Custom HTML tag and the Custom JavaScript variable, I started considering whether the custom script that needed to be deployed could be transformed into a custom template first. While publishing numerous templates into the community gallery, I always spent some time over the past 12 months tinkering on an extremely complicated template translation: the Snowplow Analytics JavaScript tracker.

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The shadow DOM is a way to add HTML structures to the web page so that they remain isolated from the rest of the document object model (DOM). It’s a popular concept with web components, as it allows for encapsulation of web structures so that they aren’t affected by style declarations of the parent tree, for example. However, being such a “hidden” structure, anything that happens in the shadow DOM is also hidden from Google Tag Manager’s listeners.

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