Expo Platform Highlights Summary

Every highlight bullet from the 10 pages in this section, gathered on one page and grouped by the page it came from.

Expo Platform Basics

• Expo is a platform layer on React Native - you still write RN components, Expo handles native project wiring
• The managed workflow keeps ios/ and android/ generated; you opt into native folders only when needed
• Pin expo ~57.0.4 in package.json - every Expo module version is validated against that SDK
• npx expo install resolves compatible semver ranges; plain npm install can drift from the SDK matrix
• Expo Go is fastest for learning; custom native modules require a development build with expo-dev-client
• app.config.ts can branch on APP_VARIANT without committing secrets to app.json
• Linking an EAS projectId early keeps builds, updates, and environment variables scoped to one Expo project

create-expo-app Quickstart

• Pin SDK 57 explicitly with --template default@sdk-57 - bare @latest may scaffold SDK 54 during the transition
• default template ships Expo Router, TypeScript, and the recommended Expo CLI scripts
• Verify the pin in package.json: expo ~57.0.4 and react-native 0.86.0
• Run npx expo-doctor after scaffold to catch version skew before you write feature code
• bare-minimum runs prebuild immediately - choose it only when you need android/ and ios/ on day one

app.json & app.config.js

• Static app.json for tooling edits; app.config.ts when you need env branches and typed config
• EXPO_PUBLIC_ vars inline at bundle time - never put secrets there
• extra passes non-secret runtime config via Constants.expoConfig.extra
• npx expo config --type public shows exactly what ships in the client bundle
• Config plugins in app.config mutate native projects at prebuild/EAS build time

Expo Go vs Development Builds

• Expo Go is a fixed native binary - only its preinstalled native modules are callable from your JS
• Development builds include expo-dev-client and YOUR native dependencies
• Switch before custom native modules, push credentials, or universal/app links
• npx expo install expo-dev-client then eas build --profile development
• JS hot reload works in both; native code changes require a new native build

Expo Modules Core

• The expo package installs ExpoModulesCore native infrastructure at app launch
• requireNativeModule resolves JSI bindings first, then falls back to legacy bridge proxies
• registerRootComponent wires AppRegistry and dev-only Fast Refresh helpers
• NativeModule and SharedObject extend EventEmitter over JSI - same API on iOS and Android
• Works in managed, bare, and brownfield apps once the native entry point is configured

Environments & EAS Environment Variables

• EAS provides three built-in environments: development, preview, and production
• Map eas.json build profiles to EAS environments with the environment field
• Only EXPO_PUBLIC_ variables are safe to embed in client JavaScript - treat them as public
• eas env:pull syncs cloud variables to .env.local for local dev without committing secrets
• SDK 55+ requires --environment on eas update so OTA bundles match build-time config
• Secret visibility variables are for build-time tooling (NPM tokens), not client-side API keys

Upgrading Expo SDK Versions

• Upgrade one SDK version at a time - never skip majors in a single PR
• npx expo install --fix realigns every Expo module to the SDK compatibility matrix
• npx expo-doctor catches unmet peer deps, config plugin drift, and New Architecture mismatches
• CNG projects delete ios/ and android/ after a bump - EAS Build regenerates them via prebuild
• SDK 57 targets React Native 0.86 with no intentional breaking changes from 0.85
• Rebuild development clients after every native-affecting SDK upgrade

Managed to Bare Migration

• Managed vs bare workflow is deprecated - Continuous Native Generation (CNG) is the modern model
• CNG generates ios/ and android/ on demand; you maintain app.config + config plugins, not native diffs
• Committing native folders opts out of automatic EAS prebuild - upgrades require manual native merges
• SDK 57 runs expo prebuild --clean by default; pass --no-clean to layer incremental changes
• Migrate native customizations to config plugins before deleting hand-edited native code
• Bare RN CLI projects can adopt prebuild without losing Expo modules or EAS services

Expo Account, Projects & Permissions

• Personal accounts suit solo work; organizations enable team RBAC and shared credentials
• Four org roles: Owner, Admin, Developer, Viewer - least privilege for day-to-day work
• Set expo.owner in app.json so builds and credentials land under the correct account
• extra.eas.projectId is the stable identifier for EAS Build, Update, and env vars
• Account-wide environment variables share tooling tokens across multiple apps
• Project transfers require Owner/Admin on both source and destination accounts

Expo Platform Best Practices

• Pin SDK at scaffold time with default@sdk-57 and verify with expo-doctor
• Use app.config.ts and EXPO_PUBLIC_ for env - never commit secrets to extra
• Adopt expo-dev-client when you need native modules beyond Expo Go
• Let npx expo install resolve SDK-compatible native dependency versions
• Gitignore ios/ and android/ under CNG; regenerate with prebuild on upgrades
• Scope EAS projects, credentials, and env vars per app under an organization