Node.js Built-in Modules
📌 Covered in this chapter:
node:path · node:fs · node:os · node:url · node:events · node:crypto · node:stream
A tour of Node's core modules — the batteries-included toolkit available without installing anything from npm.
1Node.js Built-in Modules — What You'll Learn
A tour of Node's core modules — the batteries-included toolkit available without installing anything from npm.
Here's everything this chapter covers, in the order you'll learn it:
- What built-in (core) modules are
- node:path — file path utilities
- node:fs — file system access
- node:os — operating system information
- node:url — URL parsing
- node:events — the EventEmitter class
- node:util — utility helpers
- node:crypto — hashing and cryptography
- node:buffer — binary data handling
- node:stream — streaming data
- node:zlib — compression
- node:readline — reading input line by line
- node:child_process — spawning external processes
- node:worker_threads — CPU-bound parallel work
- node:test — Node's built-in test runner
2Working Example
💻 Example: Node.js Built-in Modules
JavaScript
▶ Run in Compiler
import os from "node:os";
import path from "node:path";
console.log("Platform:", os.platform());
console.log("CPU cores:", os.cpus().length);
console.log("Joined path:", path.join("src", "routes", "users.js"));3Best Practices & Common Pitfalls
💡 Key things to remember:
- Built-in modules are prefixed with node: (recommended) — this avoids any ambiguity with npm packages of the same name.
- You never need to npm install these — they ship with the Node.js runtime itself.
❓ Frequently Asked Questions (FAQ)
Q What's the most important thing to understand about node.js built-in modules?
Focus on: node:path · node:fs · node:os · node:url · node:events · node:crypto · node:stream. These are the core building blocks this chapter's examples are built around, and they show up repeatedly in later chapters of this course.
Q Do I need external npm packages for node.js built-in modules?
Only where explicitly shown in the code examples above (like Express, Zod, or Socket.IO) — otherwise, this chapter relies entirely on Node.js's own built-in capabilities.