Interview Questions Overview
Comprehensive React interview resource with questions ranked by difficulty — from beginner to advanced.
Browse all questions →React
Complete React knowledge base covering setup, components, hooks, core concepts, advanced patterns, and modern React 19 features — from basic functional components to Server Components and Actions.
🚀 Getting Started
Section titled “🚀 Getting Started” Introduction to React What React is, Virtual DOM, Reconciliation, React vs Angular, and the declarative paradigm.
React Project Structure Recommended folder structure, file organization, and project architecture patterns.
JSX JSX syntax, expressions, attributes, and how it compiles to React.createElement calls.
Props Overview What are props, one-way data flow, component tree, and basic usage.
Prop Types String, number, boolean, array, object, function — all prop types explained.
Children Prop The special children prop for wrapping and composing components.
Default Props & Destructuring Setting default values and cleaning up code with destructuring.
Strict Mode React StrictMode, double-invocation, identifying side effects, and best practices.
Fragments React Fragments, shorthand syntax, and avoiding unnecessary DOM wrappers.
React Setup Guideline Complete setup guide with Vite, Create React App, and Next.js configuration.
🪝 Hooks Deep Dive
Section titled “🪝 Hooks Deep Dive” Hooks Overview Rules of hooks, built-in hooks catalog, and when to use each one.
useState State management, updater functions, lazy initialization, and state batching.
useEffect Side effects, dependency arrays, cleanup functions, and lifecycle mapping.
useRef DOM refs, mutable values, forwardRef, and ref callback patterns.
useMemo Memoization, expensive computations, and performance optimization.
useCallback Function memoization, referential equality, and optimizing child re-renders.
useContext Context API, provider patterns, useContext hook, and context composition.
useReducer Reducer pattern, complex state logic, action dispatching, and Redux alternative.
Custom Hooks Building reusable hooks, hook composition, and real-world custom hook examples.
useLayoutEffect Synchronous layout effects, DOM measurements before paint.
useImperativeHandle Exposing a controlled API from child to parent via ref.
useId Stable unique IDs for accessibility and SSR-safe forms.
useTransition Marking state updates as non-urgent for responsive UIs.
useDeferredValue Deferring heavy re-renders based on a value.
useSyncExternalStore Subscribing to external data stores (Redux, Zustand, browser APIs).
🧩 Component Patterns
Section titled “🧩 Component Patterns” Components Overview Complete guide to all React component types and patterns.
Functional Components Modern function-based components, hooks integration, and best practices.
Class Components ES6 class components, lifecycle methods, and legacy patterns.
Component Lifecycle Mount, update, unmount phases — class lifecycle vs hooks equivalents.
Higher-Order Components HOC pattern, wrapping components, and cross-cutting concerns.
Compound Components Flexible component composition with implicit state sharing.
Layout Components Sidebars, modals, grids, and reusable layout patterns.
Controlled vs Uncontrolled Controlled components with state vs uncontrolled with refs.
Container & Presentational Separation of concerns: smart vs dumb component architecture.
Custom Hook Components Components driven entirely by custom hooks for logic reuse.
🔗 Data Binding & Core Concepts
Section titled “🔗 Data Binding & Core Concepts” Data Binding Overview One-way data flow, state management philosophy, and binding patterns.
Data Binding Concepts State vs props, lifting state up, and data flow architecture.
Conditional Rendering Ternary, &&, switch, and conditional rendering patterns.
Lists and Keys Rendering lists, key prop importance, and index vs stable IDs.
React Events Synthetic events, event handlers, event pooling, and custom events.
Lifecycle Hooks Mapping class lifecycle to hooks for data operations.
Forms Controlled forms, form validation, and form libraries.
HTTP Methods & Axios Fetch API, Axios, API calls, loading states, and error handling.
Routing React Router, route configuration, nested routes, and navigation.
State Management Local state, Context, Zustand, Redux, and state management strategies.
Higher-Order Components HOCs for cross-cutting concerns — now redirects to canonical Components page.
⚡ Advanced Concepts
Section titled “⚡ Advanced Concepts” Error Boundaries Catching render errors, fallback UI, and error boundary placement strategies.
Suspense & Lazy Loading Code-splitting with React.lazy, Suspense fallbacks, and route-based splitting.
Portals Rendering outside parent DOM for modals, tooltips, and overlays.
Refs & forwardRef DOM access, forwardRef, useImperativeHandle, and React 19 ref-as-prop.
Performance & Memoization React.memo, useMemo, useCallback, profiling, and when memoization helps.
Reconciliation & Virtual DOM How React diffs, the role of keys, Fiber reconciler, and render cycle.
Prop Drilling What prop drilling is, why it's a problem, and how to fix it with Context API, composition, and state management.
🚀 Modern React (v19)
Section titled “🚀 Modern React (v19)” Actions & Forms React 19 Actions, form action, useActionState, useFormStatus.
useOptimistic Optimistic UI updates — show results instantly, revert on failure.
use() Hook Reading Promises and Context conditionally with Suspense integration.
Server Components RSC vs Client Components, 'use client', where each runs.
Modern React Interview Q&A for React 19 features — Actions, useOptimistic, Server Components.
🎯 Interview Preparation
Section titled “🎯 Interview Preparation”Easy Questions
JSX basics, components, props, state, and fundamental React concepts.
Start →Medium Questions
Hooks, lifecycle, context, refs, performance optimization, and patterns.
Start →Hard Questions
Advanced patterns, reconciliation internals, concurrent mode, and architecture.
Start →Quick Cheatsheet
Rapid-fire syntax reference, common hooks patterns, and quick code snippets.
View →📖 Suggested Learning Path
Section titled “📖 Suggested Learning Path”- Introduction to React — Understand what React is and how the Virtual DOM works
- JSX — Learn the JSX syntax and how it compiles to JavaScript
- Components & Props — Build your first components and pass data with props
- Hooks (useState & useEffect) — Master the two most important hooks
- Conditional Rendering & Lists — Build dynamic UIs with conditions and keyed lists
- Forms & Events — Handle user input and form submission
- State Management & Routing — Scale your app with proper state and routing
- Advanced Concepts — Error boundaries, Suspense, and performance optimization
- Modern React (v19) — Actions, useOptimistic, Server Components
- Interview Questions — Test your knowledge with real interview questions