Google Analytics 4

The GA4 plugin sends Funnel events to Google Analytics 4 through window.gtag. Because Funnel’s events already follow the GA4 schema, this plugin passes them through unchanged. No transformation needed.

What it tracks

Every Funnel event is forwarded as a GA4 event with the same name and parameters, plus an event_id (from the EventContext) for cross-platform deduplication. setUser maps to gtag("set", ...) and consent maps 1:1 to Consent Mode v2.

Before you start

A GA4 Measurement ID (looks like G-XXXXXXXXXX) from your GA4 property.
The standard GA4 base snippet (gtag.js) loaded in your page <head>, so that window.gtag exists before Funnel runs. Funnel only calls gtag; it does not load it for you.

Install & initialize

import { Funnel } from "@sunwjy/funnel-client";
import { createGA4Plugin } from "@sunwjy/funnel-client/ga4";

export const funnel = new Funnel({
  plugins: [createGA4Plugin()],
  debug: true,
});

funnel.initialize({
  ga4: {
    measurementId: "G-XXXXXXXXXX",
    // Optional: forwarded to gtag("config", id, config)
    config: { send_page_view: false },
  },
});

Track an event

funnel.track("purchase", {
  currency: "KRW",
  value: 29000,
  transaction_id: "T-1",
});

Verify

Enable debug: true on the Funnel to log each dispatch to the console.
Set config: { debug_mode: true } and open GA4 DebugView in the Google Analytics UI.
Inspect outgoing gtag calls in the browser DevTools Network tab (requests to google-analytics.com).

Notes

SSR-safe: when window (or window.gtag) is unavailable, track, setUser, and setConsent quietly skip. Nothing throws.
The config field is forwarded verbatim to gtag("config", measurementId, config), so you can control GA4 SDK behavior (send_page_view, cookie_domain, anonymize_ip, etc.).
setConsent mirrors Google Consent Mode v2 signals one-to-one (ad_storage, analytics_storage, ad_user_data, ad_personalization).