Node.js and Express.js

Node.js and Express.js are powerful tools for creating robust, scalable, and dynamic web applications. They allow developers to build backend systems that integrate seamlessly with JavaScript-based web applications. This combination streamlines web development and provides a reliable foundation for modern applications. Whether you’re building a real-time chat app, a RESTful API, or an e-commerce platform, Node.js and Express.js are indispensable technologies for the job.

In this section, we’ll cover the following topics:

Introduction to Node.js and Express.js

To deploy JavaScript-based web applications, you need a solid backend system. Node.js, with its server-side runtime, and Express.js, a minimalist framework, combine to provide a comprehensive solution. Together, they enable developers to create efficient and scalable server-side applications.

What is Node.js?

Node.js is an open-source, cross-platform runtime environment that executes JavaScript code outside the browser. Built on Google Chrome's V8 JavaScript engine, it enables server-side scripting and is widely used for creating fast, scalable network applications.

Key Features of Node.js

• Asynchronous and Event-Driven: Handles multiple requests simultaneously without blocking the main thread.
• Fast Performance: Powered by the V8 engine, it ensures quick execution of JavaScript code.
• Cross-Platform: Compatible with multiple operating systems, including Windows, macOS, and Linux.
• NPM Ecosystem: Offers a massive library of reusable packages via the Node Package Manager (npm).

What is Express.js?

Express.js is a web application framework for Node.js. It simplifies the process of creating and managing servers, routes, and APIs. By offering a flexible, unopinionated design, it allows developers to build web applications with ease.

Key Features of Express.js

• Routing: Handles different HTTP methods and URLs with its robust routing mechanism.
• Middleware: Facilitates request and response processing with modular functions.
• WebSockets: Supports real-time communication for applications like chat apps and live updates.
• Template Engines: Works with popular engines like Pug and EJS for dynamic HTML generation.

How Node.js and Express.js Work Together

Node.js provides the runtime environment, while Express.js acts as a framework that simplifies coding. Together, they offer a robust foundation for backend systems by enabling server-side scripting, efficient routing, and smooth integration with front-end frameworks.

Setting Up Node.js and Express.js

Installing Node.js and npm

1. Download the latest Node.js version from the official website.
2. Install Node.js, which includes npm (Node Package Manager).
3. Verify the installation by running node -v and npm -v in your terminal.

Setting Up Express.js

1. Create a new project directory and navigate to it in your terminal.
2. Initialize the project by running npm init -y.
3. Install Express.js with the command npm install express.

Building Your First Server with Express.js

Step 0: Check if Node.js is Installed

Open your terminal or command prompt. Run the following command to check the installed version of Node.js:

node -v

If Node.js is installed, you’ll see a version number, such as v18.17.0.

If you see an error message like command not found, it means Node.js is not installed. You need to install Node.js first. You can get it via official Node.js website.

Step 1: Create a Project Folder

Open your terminal or command prompt.

Navigate to the location where you want to create your project folder. For example:

cd your-project-parent-folder

Create a new folder for your project and move there.

mkdir express-server
cd express-server

Step 2: Initialize the Project

Run the following command to create a package.json file, which tracks project metadata and dependencies:

npm init -y

After this step, you’ll find a package.json file in your project folder.

Step 3: Install Express.js

Install Express.js as a dependency in your project:

npm install express

Once installed, you’ll see a new node_modules folder in your project directory, along with a package-lock.json file. These are managed by npm to store and track dependencies.

Step 4: Create the Server File

In your project folder, create a new file named server.js. You can use any text editor (like VS Code, Sublime Text, or Notepad++):

touch server.js

Alternatively, create it directly in your file explorer.

Open the server.js file in your editor and add the following code:

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

// Define a route
app.get("/", (req, res) => {
  res.send("Hello, World!");
});

// Start the server
app.listen(3000, () => {
  console.log("Server is running on http://localhost:3000");
});

Step 5: Start the Server

Save the server.js file. Go back to your terminal and start the server using the following command:

node server.js

If everything is set up correctly, you’ll see this message in the terminal:

Server is running on http://localhost:3000

Step 6: Test the Server

Open your browser and go to http://localhost:3000

You should see the message Hello, World! displayed on the page.

Step 7: Stop the Server

To stop the server, go back to your terminal and press Ctrl + C.

Final Directory Structure

Your project folder should now look like this:

express-server/
├── node_modules/
├── package-lock.json
├── package.json
└── server.js

Reference links:

Node.js Official Documentation

Express.js Official Website