🚀 Day 1: Introduction to Node.js — Setup, Running JavaScript in Terminal

👩‍💻 Target Audience:

• Freshers & Students learning backend

• Working professionals revising Node.js basics

• Anyone transitioning from frontend to full-stack

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🌐 What is Node.js?

Node.js is a JavaScript runtime that allows you to run JavaScript outside the browser, especially on a server.

👉 Normally, we use JavaScript in the browser (like in React or plain JS).
But with Node.js, we can use JavaScript to build:

• Web servers

• APIs

• CLI tools

• Backend logic (databases, file handling, etc.)

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🧠 Why Node.js?

Here’s why developers love Node.js:

✅ You can use the same language (JavaScript) on frontend and backend
✅ It’s fast and event-driven, suitable for real-time apps (like chats)
✅ It has a huge ecosystem (via npm) for ready-to-use libraries
✅ Used by big companies like Netflix, PayPal, LinkedIn

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🛠️ How to Setup Node.js on Your Computer

Step 1: Download Node.js

1. Visit: https://nodejs.org

2. Download the LTS version (Long-Term Support)

3. Install it like normal software (next-next-finish)

💡 Node.js comes with npm (Node Package Manager) by default.

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Step 2: Check Installation

Open your terminal or command prompt and type:

node -v

This will show Node.js version like:

v20.10.0

Now check npm:

npm -v

You’ll see something like:

10.5.0

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✍️ Writing Your First Node.js Program

Let’s create a simple program that prints your name.

Step 1: Create a File

Make a file called intro.js and write:

console.log("Hello from Node.js! My name is Payal.");

Step 2: Run the Program in Terminal

In terminal, go to the folder where intro.js is saved:

cd path-to-your-folder

Now run the file using:

node intro.js

✅ You’ll see this output:

Hello from Node.js! My name is Payal.

🎉 Congratulations! You just ran your first Node.js program.

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🎯 Real-Life Example: Create a Calculator (Addition Only)

Let's say you want to create a backend tool that calculates the sum of two numbers.

Create a file called add.js:

const num1 = 10;
const num2 = 20;

const sum = num1 + num2;

console.log("The sum is:", sum);

Run:

node add.js

Output:

The sum is: 30

👉 In real life, backend logic like this can come from a form input (e.g. on a shopping website).

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🧩 Key Concepts You Learned Today

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📝 Practice Tasks for Students

1. Create a file multiply.js to multiply two numbers

2. Write a file bio.js that prints your name, age, and city

3. Run both programs using node filename.js in terminal

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👨‍💻 For Working Professionals

Node.js enables you to:

• Automate tasks (e.g., file processing, scheduling)

• Build backend services quickly

• Work with APIs and databases using a unified language (JS)

• Integrate with frontend (React/Angular) smoothly in full-stack apps

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✅ Summary

🔹 Node.js lets you run JavaScript on your system, not just browser
🔹 It is lightweight, fast, and perfect for backend development
🔹 You wrote and ran your first backend program
🔹 Now you’re ready to build on this with file systems, servers, and databases!