A complete, structured guide for mastering React at an intermediate and senior level.
This documentation is divided into five main pillars, each containing detailed technical topics, best practices, and interview-grade explanations.

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1. JavaScript & TypeScript Foundations

This section strengthens your foundation in the two languages most commonly used with React.

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JavaScript Topics

• Variables, scope, hoisting
• Closures and lexical environment
• Prototypal inheritance
• Event loop, async execution, microtasks, macrotasks
• Promises and async/await
• this binding and arrow functions
• Destructuring, spread, rest
• Template literals
• Array and object utilities
• Modules (import, export)
• Debounce and throttle
• Shallow vs deep copy
• Error handling with try/catch
• Event bubbling and capturing
• Functional programming patterns
• Memory management and garbage collection

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TypeScript Topics

• Basic and advanced types
• Props and state typing
• Event types (React.ChangeEvent, React.MouseEvent)
• Generics for useState and useRef
• Custom hook typings
• Context and reducer typing
• Utility types (Partial, Pick, Record, ReturnType)
• Type narrowing and guards
• Strict mode in tsconfig.json
• Literal types and enums

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2. React Core & Component Architecture

Understand the underlying design principles behind React applications.

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React Fundamentals

• Virtual DOM and reconciliation
• Functional vs class components
• Declarative vs imperative UI
• Unidirectional data flow
• Render cycle and diffing algorithm
• StrictMode behavior
• Lifecycle comparison (hooks vs classes)
• Controlled and uncontrolled components
• Keys and reconciliation strategies

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JSX, Components & Props

• JSX syntax and rules
• Functional components and props
• Default props and destructuring
• Component composition
• Render props
• Conditional rendering patterns
• Avoiding prop drilling

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3. Hooks, State & Data Management

React is centered on hooks and reactive state. This section covers core and advanced patterns.

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React Hooks

• Core hooks: useState, useEffect, useRef, useContext, useReducer
• Performance hooks: useCallback, useMemo
• Layout hooks: useLayoutEffect, useImperativeHandle
• Advanced hooks: useId, useDeferredValue, useTransition, useSyncExternalStore
• Creating custom hooks
• Cleanup functions and dependency rules
• Rules of hooks

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State Management (Local & Global)

• Local state management with hooks
• Derived state
• Global state with Context API
• Combining reducers
• Preventing unnecessary re-renders

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State Management Libraries

• Redux Toolkit
• Zustand
• Recoil
• Jotai
• MobX
• XState (state machines)

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React Query (TanStack Query)

• Query and mutation patterns
• Cache management
• Pagination and infinite queries
• Background refetching
• Optimistic updates

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4. Performance, Testing & Routing

A senior-level React developer must be proficient in optimization, testing, and advanced routing.

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Performance Optimization

• React.memo and memoization strategies
• useCallback and useMemo
• Code splitting and lazy loading
• Virtualized lists (react-window, react-virtualized)
• Avoiding anonymous functions
• Render batching and concurrency features
• Profiling with React DevTools

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React Router

• BrowserRouter, Routes, Route
• useNavigate, useParams, useLocation
• Nested and dynamic routes
• Protected routes
• Lazy-loaded routes
• Route loaders and actions (React Router v6.4+)

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Forms & Controlled Components

• Controlled vs uncontrolled components
• Validation strategies
• Libraries: React Hook Form, Formik, Yup
• Custom form components
• Performance with large forms

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Testing

• Jest
• React Testing Library
• Mocking APIs and modules
• Integration testing
• E2E testing with Cypress or Playwright

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5. System Design, Next.js, Deployment & Advanced Concepts

Learn how to architect, scale, and deploy real-world React applications.

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Next.js (Full-Stack React)

• File-based routing
• SSR, SSG, ISR
• API routes
• Middleware
• Server and client components
• Image optimization
• SEO optimization

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Architecture & Best Practices

• Feature-based folder structures
• Smart vs dumb component design
• Hooks-based architecture
• Reusable UI components
• Monorepos with Nx or Turborepo
• Environment configuration

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System Design Concepts

• Component-driven design
• Reusable design systems
• Real-time updates with WebSockets
• Caching with React Query and IndexedDB
• Multi-tenant architecture
• Offline-first React apps

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Build, Deployment & Security

• Webpack and Vite
• Babel transpilation
• Dockerization
• CI/CD pipelines
• Deployment to Vercel, Netlify, AWS Amplify
• XSS, CSRF, and secure patterns for React apps

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Start Learning

Choose a topic below to begin your React learning journey.