Expo
Overview
Expo is a development platform for React Native that provides file-based routing (Expo Router), cloud builds (EAS Build), automated store submissions (EAS Submit), and over-the-air updates (EAS Update). It includes 50+ SDK modules for native device APIs and lets developers ship iOS and Android apps without managing Xcode or Android Studio.
Instructions
- When starting a new app, use
npx create-expo-app with TypeScript and set up Expo Router for file-based navigation in the app/ directory with layouts, dynamic routes, and route groups.
- When building for production, configure EAS Build profiles (
development, preview, production) in eas.json and use cloud builds instead of local builds for reproducibility.
- When deploying updates, use EAS Update for instant JavaScript-only bug fixes that bypass app store review, with channel-based routing and rollback support.
- When accessing device APIs, use Expo SDK modules (
expo-camera, expo-location, expo-notifications, expo-secure-store) and config plugins to handle native permissions without ejecting.
- When testing, use Expo Go for quick iteration on physical devices, and development builds for testing custom native modules.
- When optimizing performance, use
expo-image over the built-in Image component for caching and modern format support, and configure splash screens and app icons via app.config.ts.
Examples
Example 1: Build a mobile app with tab navigation and push notifications
User request: "Create an Expo app with tabs, push notifications, and deep linking"
Actions:
- Scaffold with
npx create-expo-app and set up Expo Router with app/(tabs)/_layout.tsx
- Configure
expo-notifications for push notifications (APNs and FCM) with config plugin
- Add deep linking via universal links in
app.config.ts
- Set up EAS Build profiles and EAS Submit for App Store and Google Play
Output: A tab-based mobile app with push notifications, deep linking, and automated store submission.
Example 2: Ship a bug fix via over-the-air update
User request: "Push an urgent fix to production without going through app store review"
Actions:
- Fix the bug in the JavaScript/TypeScript code
- Run
eas update --channel production to publish the update
- Verify the update fingerprint to ensure no native code changes are required
- Monitor rollout and use rollback if issues are detected
Output: A production fix deployed instantly to all users without waiting for app store review.
Guidelines
- Use Expo Router for navigation since file-based routing is simpler and supports deep linking automatically.
- Use EAS Build instead of local builds for reproducible, cross-platform builds without local Xcode or Android Studio.
- Use
expo-image over Image for better caching, transitions, and modern format support (WebP, AVIF).
- Store sensitive data in
expo-secure-store, never in AsyncStorage or MMKV which are unencrypted.
- Use config plugins instead of ejecting to keep managed workflow benefits.
- Use development builds for testing native modules since Expo Go does not support custom native code.
1---2name: expo3description: Assists with building, deploying, and updating React Native applications using Expo. Use when setting up file-based routing with Expo Router, configuring EAS Build and Submit, implementing over-the-air updates, or integrating Expo SDK modules for camera, location, and notifications. Trigger words: expo, expo router, eas build, eas update, expo sdk.4license: Apache-2.05---67# Expo89## Overview1011Expo is a development platform for React Native that provides file-based routing (Expo Router), cloud builds (EAS Build), automated store submissions (EAS Submit), and over-the-air updates (EAS Update). It includes 50+ SDK modules for native device APIs and lets developers ship iOS and Android apps without managing Xcode or Android Studio.1213## Instructions1415- When starting a new app, use `npx create-expo-app` with TypeScript and set up Expo Router for file-based navigation in the `app/` directory with layouts, dynamic routes, and route groups.16- When building for production, configure EAS Build profiles (`development`, `preview`, `production`) in `eas.json` and use cloud builds instead of local builds for reproducibility.17- When deploying updates, use EAS Update for instant JavaScript-only bug fixes that bypass app store review, with channel-based routing and rollback support.18- When accessing device APIs, use Expo SDK modules (`expo-camera`, `expo-location`, `expo-notifications`, `expo-secure-store`) and config plugins to handle native permissions without ejecting.19- When testing, use Expo Go for quick iteration on physical devices, and development builds for testing custom native modules.20- When optimizing performance, use `expo-image` over the built-in `Image` component for caching and modern format support, and configure splash screens and app icons via `app.config.ts`.2122## Examples2324### Example 1: Build a mobile app with tab navigation and push notifications2526**User request:** "Create an Expo app with tabs, push notifications, and deep linking"2728**Actions:**291. Scaffold with `npx create-expo-app` and set up Expo Router with `app/(tabs)/_layout.tsx`302. Configure `expo-notifications` for push notifications (APNs and FCM) with config plugin313. Add deep linking via universal links in `app.config.ts`324. Set up EAS Build profiles and EAS Submit for App Store and Google Play3334**Output:** A tab-based mobile app with push notifications, deep linking, and automated store submission.3536### Example 2: Ship a bug fix via over-the-air update3738**User request:** "Push an urgent fix to production without going through app store review"3940**Actions:**411. Fix the bug in the JavaScript/TypeScript code422. Run `eas update --channel production` to publish the update433. Verify the update fingerprint to ensure no native code changes are required444. Monitor rollout and use rollback if issues are detected4546**Output:** A production fix deployed instantly to all users without waiting for app store review.4748## Guidelines4950- Use Expo Router for navigation since file-based routing is simpler and supports deep linking automatically.51- Use EAS Build instead of local builds for reproducible, cross-platform builds without local Xcode or Android Studio.52- Use `expo-image` over `Image` for better caching, transitions, and modern format support (WebP, AVIF).53- Store sensitive data in `expo-secure-store`, never in AsyncStorage or MMKV which are unencrypted.54- Use config plugins instead of ejecting to keep managed workflow benefits.55- Use development builds for testing native modules since Expo Go does not support custom native code.
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