Node.js revolutionized backend development by bringing JavaScript to the server. This module covers everything you need to build a solid foundation — from understanding what Node.js is and how its event-driven architecture works, to mastering npm, modules, and the core built-in modules that ship with the runtime.

Most beginners jump straight into Express.js without understanding the fundamentals. This leads to:

• Confusion about async behavior and the event loop
• Poor module organization
• Security vulnerabilities from misused core modules
• Difficulty debugging production issues

This module eliminates those gaps by building mental models that senior engineers use daily.

By the end of this module, you will be able to:

💡 Not comfortable with JavaScript? Review our JavaScript fundamentals module first.

flowchart LR
    Intro["1.1 What is Node.js?"] --> Setup["1.2 Installation & Setup"]
    Setup --> REPL["1.3 REPL & CLI Basics"]
    REPL --> Arch["1.4 Architecture & Event Loop"]
    Arch --> NPM["1.5 npm & package.json"]
    NPM --> Modules["1.6 CommonJS vs ESM"]
    Modules --> Core["1.7 Core Built-in Modules"]
    Core --> Debug["1.8 Debugging"]
    Debug --> TS["1.9 Node.js + TypeScript"]

    style Intro fill:#4f46e5,color:#fff
    style Setup fill:#6366f1,color:#fff
    style REPL fill:#818cf8,color:#fff
    style Arch fill:#7c3aed,color:#fff
    style NPM fill:#059669,color:#fff
    style Modules fill:#10b981,color:#fff
    style Core fill:#d97706,color:#fff
    style Debug fill:#f59e0b,color:#fff
    style TS fill:#ef4444,color:#fff

Total estimated time: 8 hours

Understanding Node.js fundamentals is critical for:

Interactive labs to reinforce your learning:

• Node.js Lab: File System Operations
• Node.js Lab: Event Loop Simulator
• Node.js Lab: npm Package Publishing

Common interview questions from this module:

• “Explain the Event Loop in Node.js”
• “What’s the difference between process.nextTick() and setImmediate()?”
• “CommonJS vs ES Modules — when to use which?”
• “How does Node.js handle concurrent requests with a single thread?”
• “What is libuv and what role does it play?”
• “Explain the difference between blocking and non-blocking I/O”

📄 Full interview guide: Node.js Interview Questions

💡 Pro Tip: Don’t rush through this module. The fundamentals you learn here will determine how well you understand every subsequent module. Senior engineers can explain the event loop in their sleep.