fix: queue GA4 commands in the official format

src/lib/analytics/google-analytics.test.ts

@@ -0,0 +1,50 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { createGoogleAnalytics } from './google-analytics.ts';
+
+test('Google 공식 형식의 arguments 객체를 dataLayer에 적재한다', () => {
+  const storage = new Map<string, string>();
+  const appendedScripts: Array<{ src?: string }> = [];
+  const originalWindow = globalThis.window;
+  const originalDocument = globalThis.document;
+
+  Object.defineProperty(globalThis, 'window', {
+    configurable: true,
+    value: {
+      localStorage: {
+        getItem: (key: string) => storage.get(key) ?? null,
+        setItem: (key: string, value: string) => storage.set(key, value)
+      },
+      location: { origin: 'https://doricalc-holo.live' }
+    }
+  });
+  Object.defineProperty(globalThis, 'document', {
+    configurable: true,
+    value: {
+      cookie: '',
+      title: '홀로도리 계산기',
+      createElement: () => ({ async: false, src: '', dataset: {} }),
+      head: { append: (script: { src?: string }) => appendedScripts.push(script) }
+    }
+  });
+
+  try {
+    const analytics = createGoogleAnalytics('G-TEST1234');
+    analytics.grantConsent();
+    analytics.trackPageView('/cards');
+
+    const dataLayer = (globalThis.window as unknown as GoogleTagWindow).dataLayer ?? [];
+    assert.equal(dataLayer.length, 4);
+    assert.equal(Array.isArray(dataLayer[0]), false);
+    assert.equal(dataLayer[0][0], 'consent');
+    assert.equal(dataLayer[2][0], 'config');
+    assert.equal(dataLayer[3][0], 'event');
+    assert.equal(dataLayer[3][1], 'page_view');
+    assert.equal(appendedScripts[0]?.src, 'https://www.googletagmanager.com/gtag/js?id=G-TEST1234');
+  } finally {
+    Object.defineProperty(globalThis, 'window', { configurable: true, value: originalWindow });
+    Object.defineProperty(globalThis, 'document', { configurable: true, value: originalDocument });
+  }
+});
+
+type GoogleTagWindow = Window & { dataLayer?: IArguments[] };

src/lib/analytics/google-analytics.ts

@@ -4,7 +4,7 @@ const CONSENT_STORAGE_KEY = 'holodori:analytics-consent';
 const MEASUREMENT_ID_PATTERN = /^G-[A-Z0-9]+$/i;
 
 type GoogleTagWindow = Window & {
-  dataLayer?: unknown[][];
+  dataLayer?: IArguments[];
   gtag?: (...args: unknown[]) => void;
 };
 
@@ -56,7 +56,9 @@ export function createGoogleAnalytics(rawMeasurementId: string | undefined): Ana
     if (!available || !currentWindow || loaded) return;
 
     currentWindow.dataLayer ??= [];
-    currentWindow.gtag ??= (...args: unknown[]) => currentWindow.dataLayer?.push(args);
+    currentWindow.gtag ??= function googleTag(..._args: unknown[]) {
+      currentWindow.dataLayer?.push(arguments);
+    };
     currentWindow.gtag('consent', 'default', {
       analytics_storage: 'granted',
       ad_storage: 'denied',