Google Tag Manager

Google Tag Manager app for Next Commerce. Installs the GTM container on any storefront theme and pushes GA4-style ecommerce events to the dataLayer through Storefront Event Tracking, so tags in the container can forward them to GA4, Ads, or any other destination.

Settings

Setting	Notes
Enable Google Tag Manager	Nothing loads until a Container ID is also set.
Google Tag Manager Container ID	GTM-XXXXXXX.
Skip Test Orders	Suppresses purchase for orders flagged is_test.

Events pushed to the dataLayer

Storefront event	dataLayer event
page_viewed	page_view
product_category_viewed	view_item_list
product_viewed	view_item
product_added_to_cart	add_to_cart
product_removed_from_cart	remove_from_cart
checkout_started	begin_checkout
checkout_shipping_method_submitted	add_shipping_info
checkout_completed	purchase

Each ecommerce push is preceded by { ecommerce: null } as Google recommends. Items share identifiers across the funnel (item_id = product id, sku, item_variant, per-unit numeric price and discount). value on begin_checkout, add_shipping_info and purchase is item revenue (the sum of the lines' price_excl_tax; if a payload ever lacks that field the tax-inclusive total is used, so a store seeing values that include tax should check its payloads), as GA4 defines it; shipping and tax travel in their own keys.

The page_view push exists for container triggers. The Google tag inside your container already sends its own page view, so do not attach a GA4 event tag to this push or page views double-count.

The tracker runs in a frame that is a direct child of the storefront page and reaches the dataLayer through window.parent; every access is wrapped so an embedded storefront with a cross-origin parent never throws. If the container has not loaded when the first event fires, the tracker creates the dataLayer (GTM keeps it) and logs one console warning, which usually means the theme does not render the global_header app hook.

Tests

npm test

tests/tracking.test.js runs tracking.js with the platform's globals (app, analytics, window.parent) and asserts every push, plus the escaping in the snippet. No dependencies; Node 22, the version CI runs.