Best Practices for React Native + Expo

This document outlines the best practices for developing a React (and React Native) application. These guidelines are designed to ensure the project is maintainable, scalable, and efficient. By following these practices, developers can create high-quality code that is easy to understand, test, and extend.

Table of Contents

• Code Style and Structure
• Naming Conventions
• JavaScript Usage
• TypeScript Usage (Preferred)
• Performance Optimization
• UI and Styling
• Testing
• Error Handling and Logging
• State Management
• Version Control and Collaboration
• Documentation
• Additional Best Practices
• Summary

Code Style and Structure

• Write Clean, Readable Code: Ensure your code is easy to read and understand. Use descriptive names for variables and functions.
• Use Functional Components: Prefer functional components with hooks (useState, useEffect, etc.) over class components for simplicity and better performance.
• Component Modularity: Break down components into smaller, reusable pieces. Keep components focused on a single responsibility to improve reusability and testability.
• Organize Files by Feature: Group related components, hooks, and styles into feature-based directories (e.g., user-profile, chat-screen) to maintain a clear and scalable project structure.

Naming Conventions

• Variables and Functions: Use camelCase for variables and functions (e.g., isFetchingData, handleUserInput).
• Components: Use PascalCase for component names (e.g., UserProfile, ChatScreen).
• Directories: Use lowercase and hyphenated names for directories and file names (e.g., user-profile, chat-screen) to ensure consistency across the project.

Example

JavaScript Usage

• Avoid Global Variables: Minimize the use of global variables to prevent unintended side effects and maintain clean code.
• Use ES6+ Features: Leverage ES6+ features like arrow functions, destructuring, and template literals to write concise and modern JavaScript code.
• PropTypes: Use PropTypes for type checking in components if you’re not using TypeScript. However, consider switching to TypeScript for better type safety (see the TypeScript Usage section below).

TypeScript Usage (Preferred)

• Use TypeScript: Leverage TypeScript for type safety, which helps catch errors early and improves code readability. Define types for props, state, and API responses to make the code more self-documenting and easier to maintain.
• Expo: Refer to the Expo TypeScript guide for setup instructions and best practices. TypeScript is especially beneficial for larger teams and long-term projects.

Performance Optimization

• Optimize State Management: Avoid unnecessary state updates and use local state only when needed to reduce re-renders.

• Memoization: Use React.memo() for functional components to prevent unnecessary re-renders. Consider useMemo and useCallback for optimizing expensive calculations and function references.

• FlatList Optimization: Optimize FlatList with props like removeClippedSubviews, maxToRenderPerBatch, and windowSize to improve scrolling performance on large lists.
• Avoid Anonymous Functions: Refrain from using anonymous functions in renderItem or event handlers to prevent unnecessary re-renders.
• Performance Profiling: Use React DevTools to profile and optimize component renders, identifying and fixing performance bottlenecks.

UI and Styling

• Consistent Styling: Use StyleSheet.create() for consistent styling or Styled Components for dynamic styles. Ensure styles are modular and reusable.
• Optimize Image Handling: Use optimized image libraries like react-native-fast-image to handle images efficiently, reducing memory usage and improving load times.
• Design System: Use a design system or UI library like gluestack-ui to maintain consistency in the app’s look and feel across components.
• Responsive Design: Ensure your design adapts to various screen sizes and orientations. Use responsive units (e.g., percentages, Dimensions API) or libraries like react-native-responsive-screen.
• Accessibility: Ensure the app is accessible by following best practices such as proper color contrast, touch target sizes, and screen reader support. Refer to the React Native Accessibility guide.

Testing

• Write Tests: Ensure the reliability of the codebase by writing tests for components, hooks, and business logic.
  • Unit Tests: Use Jest for testing individual components and functions.
  • Integration Tests: Test interactions between components and state management.
  • End-to-End Tests: Use Detox for testing the app’s user flows on real devices.
• Test Coverage: Aim for high test coverage, especially for critical paths and reusable components, to facilitate refactoring and prevent regressions.

Error Handling and Logging

• Global Error Handling: Implement a global error boundary to catch and handle runtime errors gracefully. Use libraries like react-native-error-boundary for this purpose.
• Logging and Monitoring: Use logging libraries like Sentry or LogRocket to track errors, performance issues, and user interactions in production. This helps in debugging and improving the app over time.

State Management

• Choose the Right Tool: Depending on the complexity of the app, select an appropriate state management solution.
  • Simple Apps: Use the Context API with useReducer for managing global state.
  • Complex Apps: Consider Redux or MobX for more advanced state management needs.
• Optimize State Updates: Avoid unnecessary re-renders by using memoization techniques and keeping state as local as possible. Use tools like useSelector (Redux) or observer (MobX) to optimize performance.

Version Control and Collaboration

• Branching Strategy: Use feature branches for new features or bug fixes. Follow a consistent naming convention (e.g., feature/user-auth, bugfix/login-crash).
• Commit Messages: Write clear and descriptive commit messages. Use the format: [Type] Description (e.g., [Feat] Add login screen, [Fix] Resolve crash on logout).
• Code Reviews: Require code reviews before merging pull requests to ensure code quality and knowledge sharing. Use GitHub’s pull request features for discussions and approvals.

Documentation

• Code Documentation: Use JSDoc or TypeScript interfaces to document components, hooks, and complex logic. This helps other developers understand the code’s purpose and usage.
• Project README: Maintain an up-to-date README with:
  • Setup instructions (e.g., installation, environment setup).
  • Project structure overview.
  • Common commands (e.g., expo start, expo build).
  • Links to relevant documentation (e.g., Expo, React Native).

Additional Best Practices

• Threading Model Awareness: Understand React Native’s threading model and offload heavy computations to background threads using libraries like react-native-workers or InteractionManager to keep the UI responsive.
• Use Expo Tools: Utilize Expo’s EAS Build and Updates for continuous deployment and Over-The-Air (OTA) updates to streamline the release process.
• Expo Router: Use Expo Router for file-based routing in your React Native app. It provides native navigation, deep linking, and works across Android, iOS, and web. Refer to the official documentation for setup and usage: Expo Router Documentation.

Summary

By following these best practices, you can ensure your React Native with Expo project is clean, maintainable, and scalable. These guidelines cover everything from code style and structure to performance optimization, testing, and documentation. Adhering to these practices will help your team collaborate effectively and deliver a high-quality app.