Node.js · Lesson 1 of 7

Node.js introduction

What Node.js is, why companies use it, installing it and running your first script.

Node.js runs JavaScript outside the browser, on servers and your computer. It's built on Chrome's V8 engine and is used for REST APIs, real-time apps (chat, notifications), command-line tools and build tools such as Vite and Webpack.

Node is non-blocking: while it waits for a file, database or network call, it keeps serving other requests instead of sitting idle. That makes one Node process good at handling many connections at once.

Setup

Install the LTS version from nodejs.org (it includes npm, the package manager).
Check it in a terminal: node -v and npm -v.
Write JavaScript in a .js file and run it with node file.js.

There's no window or document in Node — instead you get modules for files, networking, processes and more.

Example code

Run with Node.js 20+

// app.js
const name = "InfoparkDaily";
const skills = ["JavaScript", "Node.js", "Express"];

console.log("Hello from " + name + "!");
console.log("Node version:", process.version);
console.log("Skills:", skills.join(", "));

Output

Hello from InfoparkDaily!
Node version: v20.18.0
Skills: JavaScript, Node.js, Express

Save the code in a file such as app.js and run node app.js. For Express lessons, run npm install express first. Names and data are fictional.

Key points

Node.js runs JavaScript on the server.
It is non-blocking and event-driven, good for I/O-heavy apps.
npm comes with Node and installs packages.
Run a file with node file.js.

Quick check

Why is Node.js good at handling many requests at once?

It creates a new thread for every request It doesn't wait idle on I/O — it handles other work meanwhile It only works with small files It compiles JavaScript to Java

Practice task

Install Node.js LTS, create hello.js that prints your name and today's date (new Date().toDateString()), and run it.

Interview corner

What is Node.js?

A JavaScript runtime built on the V8 engine that runs JavaScript outside the browser. It's event-driven and non-blocking, which suits APIs and real-time apps.

Is Node.js single-threaded?

Your JavaScript runs on a single main thread with an event loop, but Node uses a background thread pool (libuv) for some work such as file system operations and crypto, and you can use worker threads for CPU-heavy tasks.