Node.js

Introduction to Node.js

What Node.js is, how it runs JavaScript outside the browser, the event loop, installing Node, and running your first script.

Modules: CommonJS & ES Modules

Splitting code into files, require/module.exports, import/export, built-in modules, and how Node resolves modules.

npm & package.json

Initialising a project, installing dependencies and dev dependencies, semantic versioning, scripts, lockfiles, and npx.

The File System Module

Reading and writing files with fs/promises, JSON files, appending, folders, checking existence, and handling errors safely.

Path & URL Modules

Joining and resolving paths, extracting names and extensions, parsing URLs and query strings with the WHATWG URL API.

Events & the EventEmitter

Event-driven programming in Node — EventEmitter, on/once/emit, passing data, removing listeners, and the error event.

Asynchronous Programming: Callbacks, Promises & async/await

How async code runs in Node, callbacks and their problems, promises, async/await, running tasks in parallel, timeouts and error handling.

Streams & Buffers

Processing data piece by piece — Buffers, readable/writable/transform streams, pipeline, backpressure, and when streams beat reading whole files.

The HTTP Module: Building a Server

Creating a server with node:http, requests and responses, routing by method and path, status codes and headers, JSON bodies, and making HTTP requests with fetch.

Express Basics

Why frameworks, installing Express, routes and route parameters, query strings, JSON bodies, static files, and the request/response objects.

Building a REST API with Express

Designing resources and endpoints, CRUD operations, validation, consistent error responses, pagination and filtering, and testing with a REST client.

Middleware, Authentication & Error Handling

How Express middleware works, writing logging/auth middleware, the order of middleware, async errors, security middleware, and graceful error responses.

Configuration & Environment Variables

Keeping secrets out of code, process.env, .env files, validating configuration at startup, environment-specific settings, and the twelve-factor approach.

Working with Data: JSON, SQLite & Databases

Choosing storage, using a database from Node, parameterised queries, connection pooling, ORMs vs query builders, and migrations.

Testing & Debugging Node.js Apps

Unit tests with node:test or Vitest, testing APIs with Supertest, mocking, debugging with the inspector, logging, and common runtime errors.

Deploying Node.js to Production

Production readiness — process managers and containers, health checks, logging, graceful shutdown, performance, security checklist, and hosting options.