3.1 Introduction to Node.js – The Power of JavaScript on the Server

Hi Codders! 👋
I’m Vikas Sankhla, your tech guide and founder of the Web Codder YouTube channel.
Today we’re exploring a super cool topic: Node.js. 🚀

Node.js is like giving JavaScript a superhero cape so it can work on the server side too!

🌍 What Is Node.js?

Let’s start with the basics.

Node.js is a tool that lets you run JavaScript on the server. ✨

• Before Node.js, JavaScript could only run in browsers like Chrome or Firefox.
• With Node.js, JavaScript can now run on your computer’s server too.

🛠️ How Is It Different from Traditional Server Languages?

Languages like:

But Node.js is special because:

• 🌀 It’s JavaScript (so you only need to know one language for both frontend and backend).
• ⚡ It’s fast because it uses an event-driven, non-blocking model (more on that soon!).
• 🌱 It’s lightweight and scalable.

🔎 Understanding the Node.js Runtime Environment

You can think of Node.js like a kitchen. 🍳

• The ingredients = JavaScript code.
• The kitchen (Node.js) = where the code runs and gets cooked.

💡 Node.js uses Google Chrome’s V8 Engine to run JavaScript outside the browser.

🔄 What’s Inside Node.js?

• 🧱 Core Modules – Built-in tools like fs (file system), http, etc.
• 🚪 APIs – To access files, servers, databases.
• 🌐 V8 Engine – Converts JS code into machine code FAST.

⚙️ The Magic: Event-Driven, Non-Blocking I/O

Okay, this sounds tricky 😅 but let’s make it super simple.

🍔 Imagine:

• You’re at a burger shop.
• You place your order.
• Instead of making you wait at the counter until your burger is ready, they take your order and move on to the next customer.
• When your burger is ready, they call your name. 📣

That’s Node.js! ✅

It doesn’t wait for one task to finish before moving to the next. This is called:

🚀 Setting Up a Simple Node.js App

Let’s build something small but awesome. 👇

1️⃣ Install Node.js

• Go to 👉 https://nodejs.org
• Download and install it. (Pick the LTS version)

2️⃣ Check if It’s Installed

Open your terminal/command prompt:

bashCopyEditnode -v
npm -v

✅ You should see version numbers like:

CopyEditv18.16.0
9.6.7

3️⃣ Create a Basic App

• Make a folder: my-first-node
• Inside, create a file: app.js

Add this code:

jsCopyEditconsole.log("Hello from Node.js! 👋");

Now run it:

bashCopyEditnode app.js

Boom 💥 – You just ran JavaScript outside the browser!

🌱 Using npm – Node’s Superpower

What’s npm?

npm = Node Package Manager
It helps you:

• 📦 Install ready-made code (called packages)
• 🚀 Share your own code

Example: Let’s install a popular package chalk to color text.

bashCopyEditnpm init -y
npm install chalk

In your app.js:

jsCopyEditconst chalk = require('chalk');
console.log(chalk.green('Hello in green! 🌿'));

Run:

bashCopyEditnode app.js

🎉 Your text is now green!

🧱 Understanding Modules in Node.js

Node.js has a modular structure. Think of modules like LEGO blocks. 🧩

• Built-in Modules: Like fs (file system), http
• Your Own Modules: Split your code into different files and connect them

Example of a custom module:

greet.js:

jsCopyEditfunction sayHi(name) {
  console.log(`Hello, ${name}!`);
}

module.exports = sayHi;

app.js:

jsCopyEditconst greet = require('./greet');
greet('Web Codder');

🚩 Quick Recap

💡 Why Use Node.js?

• 🔥 One language everywhere (JS for frontend + backend)
• 🚀 Fast and scalable
• 🌍 Huge community & packages
• 💼 Great for APIs, real-time apps (chat, gaming)

🎯 Conclusion

Node.js is like supercharging your JavaScript skills 🚀 so you can build full-fledged web apps all by yourself.

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