> ## Documentation Index > Fetch the complete documentation index at: https://docs.abtestly.com/llms.txt > Use this file to discover all available pages before exploring further. # GA4 dataLayer integration > How ABTestly pushes an experience_impression event into window.dataLayer, and how to read the exp_variant_string field in GA4. The GA4 adapter (turn it on under [Settings → Analytics](/settings/analytics-adapters)) makes ABTestly push one event per exposure into `window.dataLayer`. Your GA4 property picks it up like any other custom event. ## The event Per (visitor, experiment, pageview): ```js theme={null} window.dataLayer.push({ event: 'experience_impression', experiment_id: '', experiment_name: '', experiment_number: '', variant_key: 'control' | 'variant-1' | …, variant_name: '', exp_variant_string: '.', }); ``` The event name is `experience_impression`. The single most useful field is `exp_variant_string`, which follows GA4's convention for experiment slicing. ## In GA4 To slice any GA4 conversion by variant: 1. **Admin → Custom definitions → Create custom dimension.** 2. **Dimension name**, "ABTestly variant". 3. **Scope**, User (persists across events for this user). 4. **User property**, `exp_variant_string`. Then in Explorations, add "ABTestly variant" as a dimension. Every built-in conversion report can now be split by variant, alongside your other GA4 dimensions. ## Where the event fires On exposure. That is once per (visitor, experiment, pageview), not once per goal, not once per session. The event lands **at the moment the variant applies**, which is what you want for attributing downstream conversions. ## Consent The GA4 adapter respects the same consent gate as ABTestly's own beacons. In deferred consent mode, the adapter waits for grant before pushing anything. If you have GA4 consent mode set up on your side, the two systems compose. ABTestly does not push its event until its own consent gate is satisfied; GA4 does not fire its conversion until its own consent mode allows it. ## In preview Adapter pushes are suppressed in preview. Your GA4 property does not see previewed exposures. ## When the SDK is not on the page If `window.dataLayer` does not exist when the exposure fires, the adapter no-ops silently and reports a first-occurrence-per-session `/err` event. Your dashboard's Snippet health panel will surface that. Fix: load `gtag.js` (or GTM's snippet) somewhere in ``, before or after ABTestly, either order works, as long as `window.dataLayer` is defined by the time an experiment first exposes. ## Other analytics adapters Same shape, different SDK calls, see [Product analytics](/product-analytics) for Segment, RudderStack, Amplitude, Mixpanel.