Google Analytics 4 Setup Skill
You are setting up Google Analytics 4 (GA4) for a project. Follow this comprehensive guide to add analytics properly.
Arguments
Parse the following from $ARGUMENTS:
- Measurement ID: Format
G-XXXXXXXXXX(required, ask if not provided) - --events: Include custom event tracking helpers
- --consent: Include cookie consent integration
- --debug: Enable debug mode for development
Step 1: Detect Project Type
Scan the project to determine the framework/setup:
Priority detection order: 1. next.config.js/ts → Next.js 2. nuxt.config.js/ts → Nuxt.js 3. astro.config.mjs → Astro 4. svelte.config.js → SvelteKit 5. remix.config.js → Remix 6. gatsby-config.js → Gatsby 7. vite.config.js + src/App.vue → Vue + Vite 8. vite.config.js + src/App.tsx → React + Vite 9. angular.json → Angular 10. package.json with "react-scripts" → Create React App 11. index.html only → Plain HTML 12. _app.tsx/jsx → Next.js (App Router check: app/ directory)
Also check for:
- TypeScript usage (tsconfig.json)
- Existing analytics (search for gtag, GA, analytics)
- Package manager (pnpm-lock.yaml, yarn.lock, package-lock.json)
Step 2: Validate Measurement ID
The Measurement ID must:
- Start with
G-(GA4 format) - Be followed by exactly 10 alphanumeric characters
- Example:
G-ABC1234567
If the user provides a UA- ID, inform them:
"You provided a Universal Analytics ID (UA-). GA4 uses Measurement IDs starting with 'G-'. Universal Analytics was sunset in July 2024. You'll need to create a GA4 property at analytics.google.com"
Step 3: Implementation by Framework
Next.js (App Router - app/ directory)
Create app/layout.tsx modification or create components/GoogleAnalytics.tsx:
tsx// components/GoogleAnalytics.tsx 'use client' import Script from 'next/script' interface GoogleAnalyticsProps { measurementId: string } export function GoogleAnalytics({ measurementId }: GoogleAnalyticsProps) { return ( <> <Script src={`https://www.googletagmanager.com/gtag/js?id=${measurementId}`} strategy="afterInteractive" /> <Script id="google-analytics" strategy="afterInteractive"> {` window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', '${measurementId}'); `} </Script> </> ) }
Add to root layout:
tsx// app/layout.tsx import { GoogleAnalytics } from '@/components/GoogleAnalytics' // Add inside <body> or <html>: <GoogleAnalytics measurementId="G-XXXXXXXXXX" />
Next.js (Pages Router - pages/ directory)
Modify pages/_app.tsx:
tsx// pages/_app.tsx import type { AppProps } from 'next/app' import Script from 'next/script' const GA_MEASUREMENT_ID = process.env.NEXT_PUBLIC_GA_MEASUREMENT_ID export default function App({ Component, pageProps }: AppProps) { return ( <> <Script src={`https://www.googletagmanager.com/gtag/js?id=${GA_MEASUREMENT_ID}`} strategy="afterInteractive" /> <Script id="google-analytics" strategy="afterInteractive"> {` window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', '${GA_MEASUREMENT_ID}'); `} </Script> <Component {...pageProps} /> </> ) }
React (Vite/CRA)
Create src/lib/analytics.ts:
typescript// src/lib/analytics.ts export const GA_MEASUREMENT_ID = import.meta.env.VITE_GA_MEASUREMENT_ID declare global { interface Window { gtag: (...args: unknown[]) => void dataLayer: unknown[] } } export const initGA = () => { if (typeof window === 'undefined') return const script = document.createElement('script') script.src = `https://www.googletagmanager.com/gtag/js?id=${GA_MEASUREMENT_ID}` script.async = true document.head.appendChild(script) window.dataLayer = window.dataLayer || [] window.gtag = function gtag() { window.dataLayer.push(arguments) } window.gtag('js', new Date()) window.gtag('config', GA_MEASUREMENT_ID) } export const pageview = (url: string) => { window.gtag('config', GA_MEASUREMENT_ID, { page_path: url, }) } export const event = (action: string, params?: Record<string, unknown>) => { window.gtag('event', action, params) }
Initialize in src/main.tsx:
tsximport { initGA } from './lib/analytics' // Initialize before render if (import.meta.env.PROD) { initGA() }
Vue 3 (Vite)
Create src/plugins/analytics.ts:
typescript// src/plugins/analytics.ts import type { App } from 'vue' import type { Router } from 'vue-router' const GA_MEASUREMENT_ID = import.meta.env.VITE_GA_MEASUREMENT_ID declare global { interface Window { gtag: (...args: unknown[]) => void dataLayer: unknown[] } } export const analyticsPlugin = { install(app: App, { router }: { router: Router }) { // Load gtag script const script = document.createElement('script') script.src = `https://www.googletagmanager.com/gtag/js?id=${GA_MEASUREMENT_ID}` script.async = true document.head.appendChild(script) window.dataLayer = window.dataLayer || [] window.gtag = function gtag() { window.dataLayer.push(arguments) } window.gtag('js', new Date()) window.gtag('config', GA_MEASUREMENT_ID) // Track route changes router.afterEach((to) => { window.gtag('config', GA_MEASUREMENT_ID, { page_path: to.fullPath, }) }) // Provide global methods app.config.globalProperties.$gtag = window.gtag } }
Nuxt 3
Create plugins/analytics.client.ts:
typescript// plugins/analytics.client.ts export default defineNuxtPlugin(() => { const config = useRuntimeConfig() const measurementId = config.public.gaMeasurementId if (!measurementId) return // Load gtag useHead({ script: [ { src: `https://www.googletagmanager.com/gtag/js?id=${measurementId}`, async: true, }, { innerHTML: ` window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', '${measurementId}'); `, }, ], }) // Track route changes const router = useRouter() router.afterEach((to) => { window.gtag('config', measurementId, { page_path: to.fullPath, }) }) })
Add to nuxt.config.ts:
typescriptexport default defineNuxtConfig({ runtimeConfig: { public: { gaMeasurementId: process.env.NUXT_PUBLIC_GA_MEASUREMENT_ID, }, }, })
Astro
Create src/components/Analytics.astro:
astro--- // src/components/Analytics.astro interface Props { measurementId: string } const { measurementId } = Astro.props --- <script is:inline define:vars={{ measurementId }} src={`https://www.googletagmanager.com/gtag/js?id=${measurementId}`} ></script> <script is:inline define:vars={{ measurementId }}> window.dataLayer = window.dataLayer || []; function gtag() { dataLayer.push(arguments); } gtag('js', new Date()); gtag('config', measurementId); </script>
Add to layout:
astro--- import Analytics from '../components/Analytics.astro' --- <html> <head> <Analytics measurementId="G-XXXXXXXXXX" /> </head> </html>
SvelteKit
Create src/lib/analytics.ts and src/routes/+layout.svelte:
typescript// src/lib/analytics.ts import { browser } from '$app/environment' export const GA_MEASUREMENT_ID = import.meta.env.VITE_GA_MEASUREMENT_ID export function initGA() { if (!browser) return const script = document.createElement('script') script.src = `https://www.googletagmanager.com/gtag/js?id=${GA_MEASUREMENT_ID}` script.async = true document.head.appendChild(script) window.dataLayer = window.dataLayer || [] window.gtag = function gtag() { window.dataLayer.push(arguments) } window.gtag('js', new Date()) window.gtag('config', GA_MEASUREMENT_ID) } export function trackPageview(url: string) { if (!browser) return window.gtag('config', GA_MEASUREMENT_ID, { page_path: url }) }
svelte<!-- src/routes/+layout.svelte --> <script lang="ts"> import { onMount } from 'svelte' import { page } from '$app/stores' import { initGA, trackPageview } from '$lib/analytics' onMount(() => { initGA() }) $: if ($page.url.pathname) { trackPageview($page.url.pathname) } </script> <slot />
Plain HTML
Add to <head>:
html<!-- Google Analytics --> <script async src="https://www.googletagmanager.com/gtag/js?id=G-XXXXXXXXXX"></script> <script> window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', 'G-XXXXXXXXXX'); </script>
Step 4: Environment Variables
Create or update .env / .env.local:
bash# For Next.js NEXT_PUBLIC_GA_MEASUREMENT_ID=G-XXXXXXXXXX # For Vite (React/Vue/Svelte) VITE_GA_MEASUREMENT_ID=G-XXXXXXXXXX # For Nuxt NUXT_PUBLIC_GA_MEASUREMENT_ID=G-XXXXXXXXXX
Add to .env.example if it exists (without the actual ID):
bash# Google Analytics 4 Measurement ID NEXT_PUBLIC_GA_MEASUREMENT_ID=G-XXXXXXXXXX
IMPORTANT: Add .env.local to .gitignore if not already present.
Step 5: Event Tracking Helpers (if --events flag)
Create a comprehensive events utility:
typescript// lib/analytics-events.ts /** * GA4 Event Tracking Utilities * * Recommended events: https://support.google.com/analytics/answer/9267735 */ type GTagEvent = { action: string category?: string label?: string value?: number [key: string]: unknown } // Core event function export const trackEvent = ({ action, category, label, value, ...rest }: GTagEvent) => { if (typeof window === 'undefined' || !window.gtag) return window.gtag('event', action, { event_category: category, event_label: label, value, ...rest, }) } // Engagement events export const trackClick = (elementName: string, location?: string) => { trackEvent({ action: 'click', category: 'engagement', label: elementName, click_location: location, }) } export const trackScroll = (percentage: number) => { trackEvent({ action: 'scroll', category: 'engagement', value: percentage, }) } // Conversion events export const trackSignUp = (method: string) => { trackEvent({ action: 'sign_up', method, }) } export const trackLogin = (method: string) => { trackEvent({ action: 'login', method, }) } export const trackPurchase = (params: { transactionId: string value: number currency: string items?: Array<{ itemId: string itemName: string price: number quantity: number }> }) => { trackEvent({ action: 'purchase', transaction_id: params.transactionId, value: params.value, currency: params.currency, items: params.items, }) } // Content events export const trackSearch = (searchTerm: string) => { trackEvent({ action: 'search', search_term: searchTerm, }) } export const trackShare = (method: string, contentType: string, itemId: string) => { trackEvent({ action: 'share', method, content_type: contentType, item_id: itemId, }) } // Form events export const trackFormStart = (formName: string) => { trackEvent({ action: 'form_start', form_name: formName, }) } export const trackFormSubmit = (formName: string, success: boolean) => { trackEvent({ action: 'form_submit', form_name: formName, success, }) } // Error tracking export const trackError = (errorMessage: string, errorLocation?: string) => { trackEvent({ action: 'exception', description: errorMessage, fatal: false, error_location: errorLocation, }) } // Custom event builder for flexibility export const createCustomEvent = (eventName: string) => { return (params?: Record<string, unknown>) => { trackEvent({ action: eventName, ...params, }) } }
Step 6: Cookie Consent Integration (if --consent flag)
Create a consent-aware wrapper:
typescript// lib/analytics-consent.ts type ConsentState = 'granted' | 'denied' interface ConsentConfig { analytics_storage: ConsentState ad_storage: ConsentState ad_user_data: ConsentState ad_personalization: ConsentState } const CONSENT_COOKIE = 'analytics_consent' // Initialize with consent mode export const initWithConsent = (measurementId: string) => { if (typeof window === 'undefined') return // Set default consent state (denied until user consents) window.gtag('consent', 'default', { analytics_storage: 'denied', ad_storage: 'denied', ad_user_data: 'denied', ad_personalization: 'denied', wait_for_update: 500, // Wait for consent banner }) // Load gtag const script = document.createElement('script') script.src = `https://www.googletagmanager.com/gtag/js?id=${measurementId}` script.async = true document.head.appendChild(script) window.dataLayer = window.dataLayer || [] window.gtag = function gtag() { window.dataLayer.push(arguments) } window.gtag('js', new Date()) window.gtag('config', measurementId) // Check for existing consent const savedConsent = getCookie(CONSENT_COOKIE) if (savedConsent) { updateConsent(JSON.parse(savedConsent)) } } // Update consent when user makes a choice export const updateConsent = (consent: Partial<ConsentConfig>) => { if (typeof window === 'undefined' || !window.gtag) return const consentState: ConsentConfig = { analytics_storage: consent.analytics_storage || 'denied', ad_storage: consent.ad_storage || 'denied', ad_user_data: consent.ad_user_data || 'denied', ad_personalization: consent.ad_personalization || 'denied', } window.gtag('consent', 'update', consentState) // Save to cookie setCookie(CONSENT_COOKIE, JSON.stringify(consentState), 365) } // Convenience functions export const acceptAll = () => { updateConsent({ analytics_storage: 'granted', ad_storage: 'granted', ad_user_data: 'granted', ad_personalization: 'granted', }) } export const acceptAnalyticsOnly = () => { updateConsent({ analytics_storage: 'granted', ad_storage: 'denied', ad_user_data: 'denied', ad_personalization: 'denied', }) } export const denyAll = () => { updateConsent({ analytics_storage: 'denied', ad_storage: 'denied', ad_user_data: 'denied', ad_personalization: 'denied', }) } // Cookie utilities function setCookie(name: string, value: string, days: number) { const date = new Date() date.setTime(date.getTime() + days * 24 * 60 * 60 * 1000) document.cookie = `${name}=${value};expires=${date.toUTCString()};path=/;SameSite=Lax` } function getCookie(name: string): string | null { const match = document.cookie.match(new RegExp(`(^| )${name}=([^;]+)`)) return match ? match[2] : null }
Step 7: Debug Mode (if --debug flag)
Add debug configuration:
typescript// For development, enable debug mode if (process.env.NODE_ENV === 'development') { window.gtag('config', 'G-XXXXXXXXXX', { debug_mode: true, }) }
Also recommend installing the Google Analytics Debugger Chrome extension.
Step 8: TypeScript Declarations
Create types/gtag.d.ts if using TypeScript:
typescript// types/gtag.d.ts declare global { interface Window { gtag: Gtag.Gtag dataLayer: object[] } } declare namespace Gtag { interface Gtag { (command: 'config', targetId: string, config?: ConfigParams): void (command: 'set', targetId: string, config: ConfigParams): void (command: 'set', config: ConfigParams): void (command: 'js', date: Date): void (command: 'event', eventName: string, eventParams?: EventParams): void (command: 'consent', consentArg: 'default' | 'update', consentParams: ConsentParams): void (...args: unknown[]): void } interface ConfigParams { page_title?: string page_location?: string page_path?: string send_page_view?: boolean debug_mode?: boolean [key: string]: unknown } interface EventParams { event_category?: string event_label?: string value?: number [key: string]: unknown } interface ConsentParams { analytics_storage?: 'granted' | 'denied' ad_storage?: 'granted' | 'denied' ad_user_data?: 'granted' | 'denied' ad_personalization?: 'granted' | 'denied' wait_for_update?: number } } export {}
Step 9: Verification Checklist
After implementation, verify:
- Measurement ID is correct format (G-XXXXXXXXXX)
- Script loads in production (check Network tab)
- Real-time reports show activity in GA4 dashboard
- Page views are tracked on navigation
- No console errors related to gtag
- Environment variables are not committed to git
- TypeScript has no type errors (if applicable)
Step 10: Summary Output
After completing setup, provide the user with:
- Files created/modified (list them)
- Environment variables needed (with example values)
- Next steps:
- Add the Measurement ID to environment variables
- Deploy and verify in GA4 Real-time reports
- Set up conversions in GA4 dashboard
- Consider adding custom events for key user actions
Common Issues & Solutions
"gtag is not defined"
- Script hasn't loaded yet; ensure async loading is handled
No data in GA4
- Check if ad blockers are preventing tracking
- Verify Measurement ID is correct
- Check browser console for errors
Double page views
- SPA router sending duplicate events; implement deduplication
GDPR Compliance
- Always implement consent mode for EU users
- Use the --consent flag to add consent management

