Node.js & Backend APIs - Practical
Guide
Event loop, Express, REST design, databases, auth and deployment - build real
backends
Complete Study Guide | Key Concepts | Examples | Practice Questions
, 1. Node.js Fundamentals
Node.js runs JavaScript outside the browser on the V8 engine. Its event loop handles thousands of concurrent
connections with non-blocking I/O - ideal for APIs.
- Single-threaded event loop + async I/O: never block it with CPU-heavy work.
- CommonJS (require) vs ES modules (import) - know both; ESM is the modern standard.
- npm scripts automate tasks; package-lock.json pins exact dependency versions.
- Environment variables (process.env) hold config and secrets - never hardcode them.
import fs from 'node:fs/promises';
// async/await: the modern style
const text = await fs.readFile('data.txt', 'utf8');
console.log(text);
// an API call without blocking the event loop
const res = await fetch('https://api.example.com/items');
const items = await res.json();
Page 1
Guide
Event loop, Express, REST design, databases, auth and deployment - build real
backends
Complete Study Guide | Key Concepts | Examples | Practice Questions
, 1. Node.js Fundamentals
Node.js runs JavaScript outside the browser on the V8 engine. Its event loop handles thousands of concurrent
connections with non-blocking I/O - ideal for APIs.
- Single-threaded event loop + async I/O: never block it with CPU-heavy work.
- CommonJS (require) vs ES modules (import) - know both; ESM is the modern standard.
- npm scripts automate tasks; package-lock.json pins exact dependency versions.
- Environment variables (process.env) hold config and secrets - never hardcode them.
import fs from 'node:fs/promises';
// async/await: the modern style
const text = await fs.readFile('data.txt', 'utf8');
console.log(text);
// an API call without blocking the event loop
const res = await fetch('https://api.example.com/items');
const items = await res.json();
Page 1
