---name: expo-react-native-javascript-best-practicesdescription: Expo React Native JavaScript best practices for clean code, functional components, performance optimization, and Expo Router navigation.---

Expo React Native JavaScript Best Practices

Guidelines for building high-quality Expo React Native applications with JavaScript, focusing on clean code, modularity, and performance.

Code Style and Structure

• Clean, Readable Code: Ensure your code is easy to read and understand. Use descriptive names for variables and functions.
• Functional Components: Prefer functional components with hooks (useState, useEffect) over class components
• Component Modularity: Break components into smaller, reusable pieces with single responsibility
• Feature-Based Organization: Group related components, hooks, and styles into feature directories (e.g., user-profile, chat-screen)

Naming Conventions

• Variables and Functions: Use camelCase (e.g., isFetchingData, handleUserInput)
• Components: Use PascalCase (e.g., UserProfile, ChatScreen)
• Directories: Use lowercase hyphenated names (e.g., user-profile, chat-screen)

JavaScript Usage

• Minimize global variables to prevent unintended side effects
• Leverage ES6+ features like arrow functions, destructuring, and template literals to write concise code
• Use PropTypes for type checking if not using TypeScript

Performance Optimization

• Avoid unnecessary state updates; use local state when needed
• Apply React.memo() to prevent unnecessary re-renders
• Optimize FlatList with the following props:
  • removeClippedSubviews
  • maxToRenderPerBatch
  • windowSize
• Avoid anonymous functions in renderItem or event handlers

UI and Styling

• Use StyleSheet.create() for consistent styling or Styled Components for dynamic styles
• Ensure responsive design across screen sizes and orientations
• Use optimized image libraries like react-native-fast-image

Best Practices

• Follow React Native's threading model for smooth UI performance
• Use Expo's EAS Build and OTA updates for deployment
• 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