Express.js Set Up

Express.js is a minimalist web framework for Node.js, designed to create web applications and RESTful APIs. Its simplicity and flexibility have made it a popular choice among developers. This tutorial will guide you through setting up an Express.js environment.

Setting Up Express.js

Prerequisites

Before setting up Express.js, ensure you have the following installed:

1. Node.js: Download and install from nodejs.org.
2. npm: Node Package Manager, included with Node.js.

Setting up Express.js, the renowned Node.js web application framework, is straightforward. By following a few simple steps, you can quickly establish the framework and start building your web applications easily.

Step 1: Create a New Project Directory

Create a new directory for your project and navigate into it using the terminal:

mkdir my-express-app
cd my-express-app

Step 2: Initialize a New Node.js Project

Initialize a new Node.js project by creating a package.json file. Run the following command and follow the prompts:

npm init

The command above will prompt you for information about your project. You can accept the defaults or provide specific details.

Step 3: Install Express.js

Install Express.js using npm:

npm install express --save

This command above adds Express.js as a dependency in your package.json file.

Step 4: Create the Server File

Set up your Express.js server by creating a new file named app.js in your project directory.

// Import Express.js module
const express = require('express');

// Initialize the Express application
const app = express();

// Define the port number for the server to listen on
const port = 3000;

// Define a route for the root URL ('/') and specify the response
app.get('/', (req, res) => {
  res.send('Hello, World!'); // Send 'Hello, World!' as the response
});

// Start the server and have it listen on the defined port
app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`); // Log a message to the console indicating the server is running
});

Step 5: Run the Server

Run your Express.js server using the following command:

node app.js

Open your web browser and visit http://localhost:3000. The page should show the text "Hello, World!"

Step 6: Reflecting Changes

If you make changes to app.js, simply refreshing the page in your browser will not reflect these changes. You must restart the server for changes to take effect. To restart the server:

1. Stop the running server by pressing Ctrl+C in the terminal.
2. Start the server again using:

node app.js

Step 7: Using Nodemon for Automatic Restart

When changes are made to app.js in a Node.js application, you can automatically restart the server using Nodemon. The Nodemon is a development tool that automatically restarts the Node.js application when it detects changes to any project file, so you don't need to restart the server manually. Install Nodemon globally:

npm install -g nodemon

Alternatively, install it as a development dependency:

npm install --save-dev nodemon

Use Nodemon to start your server:

nodemon app.js

Now, any changes you make to app.js will automatically restart the server and reflect in your browser.

Conclusion

In this tutorial, you have learned how to set up an Express.js environment, including installing the necessary components, creating a server, and understanding the basic code structure. With this foundation, you can start developing more complex applications using Express.js.