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Sachin Maurya
Sachin Maurya

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650+ Frontend Interview Questions (JavaScript, React, Next.js & More) — My Complete Prep Journey

After giving a few frontend interviews recently, I noticed a pattern.

Almost every interviewer went beyond surface-level coding questions and asked about how things actually work under the hood —

things like the event loop, React Fiber, Next.js routing, and JavaScript internals that power our apps every day.

Instead of just memorizing answers, I decided to deeply explore every topic I encountered.

So I began building a small question list.

Then it became 50.

Then 200.

And finally — a collection of over 650 questions and concepts covering everything from core JavaScript to advanced React and Next.js internals.


🔍 What’s Inside

  • 💻 JavaScript Deep Dives — event loop, call stack, microtask vs macrotask queues, shadowing, closures, promises, async/await, debouncing, throttling, memory leaks, and more.
  • ⚛️ React Concepts — reconciliation, Fiber, lifecycle with hooks, memoization, custom hooks, performance tuning, suspense, error boundaries, and rendering optimization.
  • 🔗 Next.js — SSR, SSG, ISR, RSC, parallel routing, middleware, static optimization, SEO, and API routes.
  • 🎨 UI / CSS / HTML — accessibility, animations, layouts, BEM, flexbox vs grid, performance, and responsive systems.

This isn’t just a question dump — it’s a structured learning roadmap for frontend engineers preparing for interviews or aiming to grow into senior roles.


📘 The GitHub Repository

📘 View the full guide here:

Frontend Master Prep Series (650+ Questions)

It’s a single Markdown file you can open directly in VS Code, Obsidian, or Notion for easy reading and note-taking.

Each section is cleanly structured so you can use it as a reference or learning log.


🧩 How I Built It

This list came together from:

  • Real interview questions I faced during recent rounds
  • Discussions with mentors and frontend peers
  • Topics I explored deeply using ChatGPT, MDN, and official documentation
  • Debugging challenges from my own projects like
    • GENAI Document Analyzer
    • Kreate Energy Platform
    • Kreate Technologies

Each section evolved organically as I learned — not just what to answer, but why things work that way.


💬 What’s Next

I’m planning to release:

  • 🧾 A PDF cheat sheet (condensed quick notes for revision)
  • 🧠 A Notion version for interactive prep and progress tracking
  • 📚 A topic-wise resource roadmap with links to docs and tutorials

If that sounds useful, comment below — I’ll make them public soon.


🧠 Why I Wrote This

Because frontend interview prep shouldn’t be about memorizing buzzwords —

it should be about understanding what makes the web actually work.

This guide started as a personal learning log, but I realized it could help others too.

If it helps even one developer feel more confident walking into their next interview, it’s worth every late-night deep dive into React Fiber, microtask queues, and performance tuning.


⭐ If you find it helpful, consider starring the GitHub repo and sharing it with someone preparing for frontend interviews.

Let’s make learning a bit easier for the next person in line.


frontend #react #nextjs #javascript #webdevelopment #career #interviewprep #learningjourney

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