Node.js for Beginners

Install Express.js

🚀 Introduction

Express.js is a fast, lightweight, and flexible web framework for Node.js. Before building web applications or REST APIs with Express, you need to install Node.js, initialize a project, and add the Express package using npm.

Information

Express.js is distributed as an npm package and requires Node.js to be installed on your system.

📋 Prerequisites

Install Node.js (includes npm).
Use a code editor such as Visual Studio Code.
Basic familiarity with the command line.

🛠 Installation Steps

1️⃣

Install Node.js on your computer.

2️⃣

Create a new project folder.

3️⃣

Initialize the project using npm init.

4️⃣

Install Express.js using npm install express.

5️⃣

Create your first Express application and start the server.

📁 Step 1: Create a Project Folder

Create Project Directory

mkdir express-app
cd express-app

This creates a new folder named express-app and navigates into it.

📦 Step 2: Initialize the Project

Initialize package.json

npm init -y

The command generates a package.json file that stores your project's metadata, scripts, and dependencies.

Tip

The -y option automatically accepts the default values, making project initialization quicker.

⬇️ Step 3: Install Express.js

Install Express

npm install express

This command downloads Express.js and its required dependencies into the node_modules directory and records it under the dependencies section of package.json.

📂 Project Structure After Installation

express-app

node_modules/

package.json

package-lock.json

📝 Step 4: Create Your First Express Application

index.js

const express = require('express');

const app = express();

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

const PORT = 3000;

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

▶️ Step 5: Run the Application

Start the Server

node index.js

Open your browser and visit http://localhost:3000. You should see the message "Welcome to Express.js!".

Success

Congratulations! Your first Express.js server is now running successfully.

📄 Understanding package.json

Field	Description
name	Name of the project.
version	Current version of the application.
main	Entry point of the application.
scripts	Commands used to run the project.
dependencies	Lists installed packages such as express.

📌 Verifying the Installation

Check Installed Packages

npm list express

This command displays the installed version of Express.js in your project.

⚡ Installing Express Globally (Optional)

In most cases, Express.js should be installed locally within each project. If you want to install the express-generator tool globally to quickly scaffold applications, use the following command:

Install Express Generator

npm install -g express-generator

Important

Install Express.js locally for each project. The global installation is intended only for the express-generator utility, not the Express framework itself.

💡 Best Practices

Initialize every project with package.json.
Install Express locally using npm install express.
Keep dependencies updated regularly.
Use version control to manage your project files.
Organize application code into folders such as routes, controllers, and middleware as the project grows.

📚 Learn More

Visit the official resources for more information:
• Node.js Official Website
• Express.js Official Documentation

📝 Summary

Summary

Installing Express.js involves creating a project directory, initializing it with npm, installing the Express package, creating a simple server, and running the application. Once installed, Express.js provides a powerful foundation for building modern web applications and RESTful APIs with Node.js.