Engineering guide
Expo and React Native Coding Best Practices
Good React Native code is not only code that works on one screen. A production Expo app needs clear boundaries, predictable data flow, safe native behavior and conventions that remain understandable as the product grows.
Organize code around product features
Keep routing files thin and move product logic into feature modules, hooks and services. A screen should coordinate rendering and user interaction; it should not also own API clients, storage details, validation rules and analytics naming.
Stable feature boundaries make the codebase easier to test, replace and extend. They also give AI coding tools clearer context, which reduces accidental coupling across unrelated parts of the app.
- Keep route files focused on composition and navigation
- Co-locate feature-specific UI, hooks, types and tests
- Place shared primitives in intentionally small shared modules
- Avoid generic utility folders that become dependency catch-alls
Use TypeScript at every external boundary
TypeScript catches mistakes inside the codebase, but network responses, deep-link parameters, environment variables and persisted values remain untrusted at runtime. Validate those boundaries before the data reaches the rest of the app.
Prefer explicit domain types and narrow unions over broad objects or repeated type assertions. A small amount of precise modeling prevents entire classes of loading, navigation and purchase-state bugs.
Separate server state from interface state
Use a server-state library such as TanStack Query for remote data, caching, retries and invalidation. Keep temporary interface state close to the component that owns it, and reserve global context for state that genuinely spans unrelated parts of the app.
Do not copy query results into another global store without a clear reason. Multiple sources of truth create stale screens and make optimistic updates harder to reason about.
Treat performance and accessibility as architecture
Measure before optimizing, but make safe defaults part of the component system. Use virtualized lists for large collections, stable keys, appropriately sized images and memoization only where profiling shows real work.
Interactive controls need accessible names, adequate touch targets, visible focus behavior on web and support for dynamic text. Accessibility is easier when primitives enforce it rather than when every screen remembers it independently.
Test behavior and observe production failures
Test business rules, hooks and critical user flows instead of locking tests to implementation details. Authentication, purchases, onboarding and offline recovery deserve integration or end-to-end coverage because they cross several system boundaries.
Error tracking and analytics should use documented event names and exclude secrets or personal data. Production telemetry closes the gap between code that passed locally and code running across real devices and network conditions.
- Run linting, type checks and focused tests in CI
- Cover loading, empty, error and offline states
- Report actionable errors with useful non-sensitive context
- Document architectural decisions next to the codebase
Related technical documentation
Continue with the implementation details in these Expo Boilerplate docs:
Where Expo Boilerplate fits
Expo Boilerplate is built for developers who want a production-ready React Native foundation without spending the first weeks of a project wiring common infrastructure. It gives you a practical starting point for app features, monetization, analytics, notifications and release preparation.
FAQ
What is the best folder structure for an Expo app?
Use Expo Router for route entry points and organize most business logic by product feature. Keep shared UI primitives, configuration and infrastructure separate, but avoid creating global folders for code used by only one feature.
Should every React Native component use memoization?
No. Memoization adds complexity and only helps when it prevents measurable repeated work. Profile the app first and prioritize lists, image loading, expensive calculations and unnecessary state updates.
How do I keep an Expo app maintainable?
Use strict types, validate external data, define feature boundaries, keep one source of truth for each kind of state, test critical flows and document the conventions contributors need to follow.