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The Happy TaggerThe Happy Tagger
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Reliability & advanced

Errors, performance, dedup, cross-domain, iframes, Custom HTML and server-side.

8 lessonsAdvancedSelf-paced
0 of 8 complete0%
Module 1

Advanced

8 lessons
  1. 1

    JavaScript error tracking

    Trigger a page error and catch it with GTM's JavaScript Error trigger.

  2. 2

    Promise rejection tracking

    Catch unhandledrejection beyond gtm.pageError.

  3. 3

    Web Vitals to dataLayer

    Push LCP / CLS / INP via PerformanceObserver and tag them.

  4. 4

    Tag firing options & dedup

    Use fire-once and trigger limits to stop double-fires.

  5. 5

    Custom HTML tag

    Inject a pixel via a Custom HTML tag and learn its sandbox limits.

  6. 6

    Cross-domain linker

    Decorate cross-domain links and verify the _gl parameter.

  7. 7

    iframe postMessage bridge

    Capture events from an embedded iframe into the parent dataLayer.

  8. 8

    Server-side GTM

    Forward events to a server container and reshape them (needs a backend).