**Course Title:** Mastering Node.js: Building Scalable Web Applications **Section Title:** Working with the Express Framework **Topic:** Setting up an Express server In this topic, we will cover the essential steps to set up an Express server, including creating a new Express application, configuring middleware, and defining routes. By the end of this topic, you will have a solid understanding of how to create a basic Express server and be ready to move on to more advanced topics. ### Prerequisites Before starting this topic, make sure you have: * Node.js installed on your machine (download from [https://nodejs.org/en/download/](https://nodejs.org/en/download/)) * A basic understanding of JavaScript and Node.js concepts * Familiarity with the Express framework (covered in the previous topic) ### Setting up an Express Server To create a new Express server, follow these steps: #### Step 1: Create a new Express application Open your terminal or command prompt and run the following command to create a new Express application: ```bash npx express-generator ``` This will create a new directory called `express-example` with a basic Express application structure. #### Step 2: Navigate to the project directory Navigate to the project directory using the following command: ```bash cd express-example ``` #### Step 3: Install dependencies Install the required dependencies by running the following command: ```bash npm install ``` #### Step 4: Start the server Start the server by running the following command: ```bash npm start ``` This will start the server on port 3000. ### Configuring Middleware Middleware is a function that has access to the request object (req), the response object (res), and the next middleware function in the application's request-response cycle. Express provides several built-in middleware functions, including: * `express.static()`: serves static files from a directory * `express.json()`: parses JSON requests * `express.urlencoded()`: parses URL-encoded requests To configure middleware, add the following code to the `app.js` file: ```javascript const express = require('express'); const app = express(); app.use(express.static('public')); app.use(express.json()); app.use(express.urlencoded({ extended: true })); app.listen(3000, () => { console.log('Server started on port 3000'); }); ``` ### Defining Routes Routes are used to handle HTTP requests and send responses back to the client. To define routes, use the `app.get()`, `app.post()`, `app.put()`, and `app.delete()` methods. For example, to define a route for the root URL (`/`), add the following code: ```javascript app.get('/', (req, res) => { res.send('Hello World!'); }); ``` ### Conclusion In this topic, we covered the essential steps to set up an Express server, including creating a new Express application, configuring middleware, and defining routes. By following these steps, you can create a basic Express server and be ready to move on to more advanced topics. ### What's Next? In the next topic, we will cover "Understanding routing in Express (GET, POST, PUT, DELETE)". ### Leave a comment or ask for help If you have any questions or need help with setting up an Express server, leave a comment below.