Welcome to Node.js Interview Prep

This course covers the Node.js concepts interviewers actually probe on: the runtime and event loop, the module system, core modules, streams and buffers, async patterns, Express.js, database integration, authentication and security, testing, and shipping Node.js to production.

What You'll Learn

• Node.js Internals - Runtime vs language, event loop phases, libuv and the thread pool, V8 memory and GC, blocking vs non-blocking
• Module System - CommonJS require/module.exports, ES Modules, resolution and package.json
• Core Modules - fs, path, os, events (EventEmitter), http from scratch, crypto
• Streams and Buffers - Buffers, Readable/Writable/Duplex/Transform, pipe() and backpressure, real-world stream patterns
• Asynchronous Patterns - Error-first callbacks, Promises and async/await, error handling strategy, worker threads
• Express.js Essentials - Middleware, routing, error-handling middleware, request validation, security
• Database Integration - Connection pooling, ORMs and query builders, the repository pattern, Redis caching
• Authentication and Security - JWT (access + refresh), session-based auth, OAuth / social login, OWASP top issues
• Testing - Unit testing with Jest, integration testing with Supertest, testing strategies for backend code
• Production and Scaling - cluster and PM2, logging and monitoring, env config, Dockerizing Node.js, interview question bank

How to Use This Course

Read the chapters in order - later chapters lean on the internals from Chapter 1. After each lesson, close the file and re-explain the concept out loud. Chapter 10's last lesson is the interview question bank - save it for the end as a self-test.

Prerequisites

• Working JavaScript knowledge (covered in the JS course)
• Familiarity with the terminal and a package manager (npm, pnpm, or yarn)
• Node.js 20+ installed locally

Let's start with the runtime itself.