Learn Node.js — Beginner Tutorial

Introduction

Node.js is a runtime environment that lets you run JavaScript on the server side — not just in the browser.
It’s fast, scalable, and widely used for building APIs, web servers, and real-time apps.

Prerequisites

Before you start:

Install Node.js (v18 or later): https://nodejs.org
Install Visual Studio Code or any text editor
Basic knowledge of JavaScript

Step 1 — Check Node Installation

Open your terminal or command prompt and run:


node -v
npm -v

You should see the installed versions of Node.js and npm (Node Package Manager).

Step 2 — Create Your Project

Create a new folder:


mkdir my-node-app
cd my-node-app

Initialize a Node.js project:


npm init -y

This creates a package.json file to manage your project and dependencies.

Step 3 — Create a Simple App

Create a file named app.js:


// app.js
console.log("Hello from Node.js!");

Run it:


node app.js

✅ Output:


Hello from Node.js!

Step 4 — Create a Simple HTTP Server

Replace your app.js content with:


const http = require('http');

const server = http.createServer((req, res) => {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello, Node.js Server!');
});

server.listen(3000, () => {
  console.log('Server running at http://localhost:3000');
});

Run:


node app.js

Open http://localhost:3000 — you’ll see:


Hello, Node.js Server!

Step 5 — Use External Packages

Install a popular package (e.g. Express, a web framework):


npm install express

Update your app.js:


const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Hello Express!');
});

app.listen(3000, () => {
  console.log('Server running at http://localhost:3000');
});

Run again:


node app.js

Visit http://localhost:3000 — you’ll see:


Hello Express!

Step 6 — Auto Restart with Nodemon

Install Nodemon globally:


npm install -g nodemon

Run:


nodemon app.js

Now your server restarts automatically whenever you change your code.

Step 7 — Create a Simple API

Add this route or update app.js:


const express = require('express');
const app = express();

const PORT = 3000;

app.get('/api/users', (req, res) => {
  const users = [
    { id: 1, name: 'Souy' },
    { id: 2, name: 'Leng' },
  ];
  res.json(users);
});

app.get('/', (req, res) => {
  res.send('Hello Express!');
});

app.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}`);
});

Try visiting:
👉 http://localhost:3000/api/users

✅ You’ll see a JSON response!

Step 8 — Summary

You just learned how to:

Run JavaScript with Node.js
Create an HTTP server
Use Express.js
Create a REST API
Auto-restart with Nodemon

Souy Soeng