Hands-on module
Tag hygiene & delivery
Stop tags double-firing and use Custom HTML as the deliberate last resort.
A growing container collects bad habits: tags that double-fire and count a conversion twice, and one-off pixels stuffed into Custom HTML. This module is about delivering tags cleanly.
You'll stop a double-fire with Tag firing options, then meet Custom HTML, the escape hatch for a vendor pixel with no template, along with its sandbox rules and when to reach for it (rarely).
What you'll learn
- Stop a tag double-firing with Tag firing options (Once per event / page)
- Inject a vendor pixel with a Custom HTML tag
- Work within the Custom HTML sandbox (no document.write after load, add an id guard)
- Know why a template or native tag beats Custom HTML almost every time
Lessons
- 1→
Why A Tagger Needs JavaScript
The point where the GTM UI runs out, and code begins.
- 2→
Values, Variables & Types
Strings, numbers, booleans, and why types bite you.
- 3→
Arrays, Objects & Loops
The data shapes GA4 ecommerce is built from.
- 4→
Where GTM Runs Your Code
Custom JS variables vs Custom HTML tags.
- 5→
Reshaping Data For GA4
Adapting a messy dataLayer to vendor requirements.
- 6→
Writing Event Listeners
Catching interactions GTM doesn't track by default.
- 7→
DOM Scraping, Safely
Reading values off the page without breaking it.
- 8→
Using AI, And Verifying It
Go faster with AI without shipping hallucinated code.
- 9→
Tag Firing Options & Dedup
Use fire-once and trigger limits to stop double-fires.
- 10→
Custom HTML Tag
Inject a pixel via a Custom HTML tag and learn its sandbox limits.
- 11→
Tag Hygiene & Delivery: Recap And Verify
Recap every lesson, then check your whole container in one pass.