Glossary

Node.js · Reference cheat sheet

📋 Overview

Alphabetical glossary of Node.js runtime, modules, and server-framework terms.

Term	Definition
Buffer	Fixed-size binary data type for bytes.
CJS	CommonJS modules using `require` / `module.exports`.
Event loop	Core scheduler for timers, I/O, and microtasks.
ESM	ECMAScript modules using `import` / `export`.
Express	Minimal, unopinionated HTTP framework.
Fastify	Schema-oriented, high-performance HTTP framework.
libuv	C library providing Node’s async I/O and threadpool.
Middleware	Function in a pipeline that can handle or forward a request.
npm	Default package manager and registry client.
package.json	Manifest for deps, scripts, and package metadata.
Plugin (Fastify)	Encapsulated unit of routes, hooks, and decorations.
semver	Semantic versioning (`major.minor.patch`).
Stream	Abstract interface for streaming data (readable/writable).
Worker thread	Separate V8 isolate for CPU-heavy work.
`node:` prefix	Built-in module import specifier (`node:fs`).

Built-in import:

import fs from "node:fs/promises";
import { createServer } from "node:http";

Detect ESM vs CJS mentally:

{ "type": "module" }

// with "type": "module" → import works
// without → require is default unless .mjs