react-refactoring-checklist.md

🚀 React Refactoring Checklist (Scalability & Maintainability)

🔍 Code Structure

• Adopt feature-based or domain-driven folder structure
• Colocate related files (component + hooks + styles)
• Avoid deep nesting (>4 levels is a red flag)
• Move reusable UI to shared/ui/ (buttons, modals)

⚛️ Components

• Split monolithic components into smaller ones
• Follow Single Responsibility Principle
• Use composition (<Card><Header /></Card>)
• Convert class components to functional + hooks

🧠 State Management

• Eliminate prop drilling (use Context/Zustand)
• Separate server state (TanStack Query) from client state
• Avoid unnecessary global state
• Memoize selectors in Redux/Zustand

⚡ Performance

• Memoize components with React.memo
• Cache expensive calcs with useMemo
• Prevent re-renders with useCallback
• Lazy-load routes (React.lazy + Suspense)
• Virtualize long lists (react-window)

🛡️ Type Safety

• Migrate to TypeScript (or add PropTypes)
• Define strict types for API responses
• Use generics for reusable hooks

🧪 Testing

• Add unit tests (React Testing Library)
• Test critical user flows (login, checkout)
• Mock API calls (MSW/fetch-mock)

✨ Code Quality

• Enforce consistent naming (PascalCase, camelCase)
• Setup ESLint/Prettier (shared config)
• Document components (Storybook/JSDoc)
• Add error boundaries

🔄 Refactoring Process

1. Identify "code smell" components
2. Write tests before refactoring
3. Refactor in small, verified steps
4. Verify no regressions