hooks
useState Hook — Complete Interview Guide
Master useState: snapshot model, functional updates, immutability, batching, lazy init, controlled inputs, and every edge case asked in React interviews.
useCallback Hook — Complete Interview Guide
Learn exactly when useCallback prevents re-renders and when it's wasted overhead — the most misused hook in React.
Custom hook — Complete Interview Guide
Learn React custom hooks with real-world examples like useFetch and useForm.
useMemo Hook — Complete Interview Guide
Learn React useMemo with real examples, performance optimization tips, and differences with useCallback.
useReducer Hook — Complete Interview Guide
Learn useReducer for managing complex state with named transitions — and how it pairs with useContext to replace Redux in mid-sized apps.
useContext Hook — Complete Interview Guide
Master React Context for sharing state across the component tree — and learn the re-render trap that catches every developer.
useRef Hook — Complete Interview Guide
Master useRef for DOM access, mutable values, and breaking stale closures — without triggering re-renders.
useEffect Hook — Complete Interview Guide
Master useEffect: dependency array, cleanup, stale closures, data fetching, race conditions, and every pattern asked in React interviews.
Core
Rendering Reconciliation
What actually happens when state changes — re-renders, virtual DOM, diffing, keys, and the two-phase render model explained precisely.
Fiber Architecture
How React works under the hood — the linked list of work units, double buffering, cooperative scheduling, and why Concurrent Mode was impossible before Fiber.
Concurrent Rendering (18)
What changed in React 18 and why it matters — startTransition, useDeferredValue, automatic batching, flushSync, and the atomic commit guarantee explained precisely.
Component Lifecycle — Complete Interview Guide
Master every phase of the React component lifecycle — mounting, updating, and unmounting.
Virtual DOM & Diffing Algorithm — Complete Interview Guide
Understand exactly how React's Virtual DOM works, how the diffing algorithm finds changes in O(n), why keys are critical for list performance, and where React Fiber fits in — with every answer an interviewer could want.
Error Boundaries — Complete Interview Guide
Master React Error Boundaries — how they catch render errors, the difference between getDerivedStateFromError and componentDidCatch, what they do and don't catch, and how to build resilient UIs that survive component crashes.
Portals — Complete Interview Guide
Understand React Portals — how createPortal teleports DOM output outside the component's parent while keeping it inside the React tree, why this solves stacking context problems, and how events still bubble correctly.
Props & One-Way Data Flow — Complete Interview Guide
Master React props — immutability, one-way data flow, lifting state up, the children prop, prop drilling, and the TypeScript patterns for typing props correctly in every interview scenario.
Performance
Forms
State
Context API — Complete Interview Guide
Master the React Context API — how to avoid prop drilling, when context re-renders every consumer, the performance optimization pattern, and the honest answer to 'Context vs Redux' that interviewers want to hear.
State Management Patterns — Complete Interview Guide
Master React state management — when to use local state, when to lift state, when Context is the right tool, and when to reach for Zustand or Redux.