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name: google-analytics description: | GA4 event tracking patterns and taxonomy. Use when: implementing analytics, tracking user events, e-commerce tracking. Do not use for: general performance optimization (use performance-patterns skill). Workflow: Set up after core features are built.

Google Analytics (GA4)

For Nextjs with GA4, see NextjsGA4 docs.

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Setup

For setup instructions:

• Next.js: See @next/third-parties docs
• ExpoReact Native: See @expo/react-native-google-analytics

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Event Naming

Rule: Use snake_case for all event names and parameters.

Copy// ✅ Good
{ event: 'add_to_cart', item_id: 'SKU123' }

// ❌ Bad  
{ event: 'AddToCart', itemId: 'SKU123' }

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Event Taxonomy

Wrap analytics calls in a centralized module:

Copy// lib/analytics.ts
export const Analytics = {
  // Auth
  signUp: (method: string) => track('sign_up', { method }),
  login: (method: string) => track('login', { method }),

  // E-commerce
  viewItem: (item: Item) => track('view_item', {
    currency: 'USD',
    value: item.price,
    items: [{ item_id: item.id, item_name: item.name, price: item.price }],
  }),
  
  addToCart: (item: Item, quantity: number) => track('add_to_cart', {
    currency: 'USD',
    value: item.price * quantity,
    items: [{ item_id: item.id, item_name: item.name, quantity }],
  }),
  
  purchase: (txId: string, value: number, items: Item[]) => track('purchase', {
    transaction_id: txId,
    value,
    currency: 'USD',
    items: items.map(i => ({ item_id: i.id, item_name: i.name, price: i.price })),
  }),

  // Engagement
  search: (term: string) => track('search', { search_term: term }),
};

Rule: Never call tracking functions directly in components. Use centralized Analytics object.

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E-commerce Flow

Standard GA4 e-commerce funnel:

Copyview_item → add_to_cart → begin_checkout → purchase

Rule: Mark conversions in GA4 Admin → Events → Toggle "Mark as conversion"

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User Tracking

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Consent Mode (GDPR)

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Quick Checklist

• GA4 measurement ID configured
• Events use snake_case naming
• Centralized Analytics module (not scattered tracking calls)
• Conversions marked in GA4 Admin
• E-commerce events follow standard schema
• Consent mode implemented (if GDPR applies)