Mastering React.js Interviews: From 0 to Hero

by Kristiyan Velkov

This book is your complete roadmap to crushing React.js 19 interviews and rising above the competition.
Based on 350+ real-world front-end interviews, it delivers the most relevant technical questions asked by top companies—along with clear, practical answers that help you build confidence, deepen your React.js knowledge, and prove your skills where it matters most.
What’s InsideCore React Concepts – JSX, Virtual DOM, props, state, and component structure (React.js v19)Hooks Deep Dive – useState, useEffect, useReducer, useRef, useMemo, and more (React.js v19)Performance Optimization – Avoid re-renders, lazy loading, memoization, and profiling (React.js v19)Component Design & Reusability – HOCs, render props, children, and Fragments (React.js v19)Forms & Event Handling – Controlled/uncontrolled components, validation, synthetic events (React.js v19)Styling Techniques – CSS Modules, Tailwind CSS (v4.0), clsx (v2.1), and scalable styling strategiesRouting – Nested routes, useParams, useSearchParams, and route protection (React Router v7.4)Error Handling – Error boundaries, debugging practices, graceful fallbacks (React.js v19)Global State Management – Context API (React 19), Redux Toolkit (v2.6), Zustand (v5.0), and best practices
Who This Book Is For ?Beginner Developers – If you're new to React.js, this book will build a strong foundation, helping you understand the core concepts and prepare for entry-level technical interviews.Intermediate Developers – If you already have experience with React.js, this book will deepen your knowledge, reinforce best practices, and prepare you for mid-level interviews.
What Makes This Book Different?Real Insights from a Technical Lead – Gain first-hand knowledge from a Front-end expert who has conducted 350+ React.js interviews.Hands-On Learning – Work through practical coding exercises and real-world scenarios to apply what you learn.Common Interview Pitfalls & Best Practices – Learn the mistakes that trip up candidates and how to stand out in interviews.Up-to-Date with React 19 & Latest Tools – Covers React.js 19, React Router v7.4, Redux Toolkit v2.6, Tailwind CSS v4.0, Zustand v5.0, and more.
What’s Inside Each Question?Every question follows a structured format designed to maximize your understanding and

Detailed Answer – A clear and in-depth explanation of the concept.Short Answer – A quick summary for rapid review.Code Examples – Practical TypeScript-based examples demonstrating real-world usage.Common Pitfalls & Best Practices – Learn what mistakes to avoid and how to write optimal code.Fun Facts – Insightful historical or technical trivia related to React.js.Resources for Further Learning – Links to official documentation, articles, and other trusted sources to dive deeper.

Kindle Edition

Published March 20, 2025

About the author

Kristiyan Velkov is a seasoned front-end developer, author, and tech educator with over a decade of experience in web development. Specializing in React.js, Next.js, TypeScript, and JavaScript, he shares his expertise through books, blog posts, and community contributions. Kristiyan is passionate about clean code, performance optimization, web security, and accessibility.

He is the author of Mastering TypeScript Core Utility Types and React.js Interview Questions, providing in-depth technical knowledge and practical insights for developers at all levels. An active writer on Medium with thousands of followers, Kristiyan also contributes to open-source projects and engages with the developer community through speaking events and workshops.

Beyond coding, he is committed to personal growth, productivity, and Stoic philosophy. His goal is to help developers refine their skills, navigate technical challenges, and excel in their careers.

Find him on Medium: @kristiyan.velkov
LinkedIn: Kristiyan Velkov