**Course Title:** Mastering Express.js: Building Scalable Web Applications and APIs **Section Title:** Introduction to Node.js and Express.js **Topic:** Set up a Node.js and Express.js development environment and create a simple web server with basic routes.(Lab topic) **Objective:** By the end of this topic, you will be able to set up a Node.js and Express.js development environment, create a simple web server, and define basic routes using Express.js. This hands-on lab topic aims to help you apply the concepts learned in the previous topics and gain practical experience in building web applications with Node.js and Express.js. **Materials Needed:** * Node.js (version 18.x or later) [Download Node.js](https://nodejs.org/en/download/) * Express.js (version 4.x or later) [Express.js Documentation](https://expressjs.com/en/4x/api.html) * A code editor or IDE (such as Visual Studio Code, Sublime Text, or Atom) * A terminal or command prompt **Step 1: Verify Node.js and npm Installation** Before proceeding, ensure that Node.js and npm (Node Package Manager) are installed on your system. To verify the installation, open a terminal or command prompt and execute the following commands: ```bash node -v npm -v ``` This should display the version numbers of Node.js and npm installed on your system. **Step 2: Create a New Project Directory and Initialize a New Node.js Project** Create a new directory for your project and navigate to it in the terminal or command prompt: ```bash mkdir my-express-app cd my-express-app ``` Next, initialize a new Node.js project using the following command: ```bash npm init ``` This will prompt you to enter information about your project. Fill in the required fields as desired, and a `package.json` file will be created in your project directory. **Step 3: Install Express.js** Install Express.js using npm by executing the following command: ```bash npm install express ``` This will install Express.js and add it to the dependencies in your `package.json` file. **Step 4: Create a Simple Web Server** Create a new file named `app.js` in your project directory and add the following code to create a simple web server: ```javascript const express = require('express'); const app = express(); const port = 3000; app.get('/', (req, res) => { res.send('Hello from Express.js!'); }); app.listen(port, () => { console.log(`Server started on port ${port}`); }); ``` This code creates an Express.js application instance, defines a GET route for the root URL ('/'), and starts the server listening on port 3000. **Step 5: Run the Web Server** Execute the following command to start the web server: ```bash node app.js ``` Open a web browser and navigate to `http://localhost:3000/`. You should see the message "Hello from Express.js!". **Step 6: Create Basic Routes** Update the `app.js` file to include additional routes: ```javascript const express = require('express'); const app = express(); const port = 3000; app.get('/', (req, res) => { res.send('Welcome to the home page!'); }); app.get('/about', (req, res) => { res.send('Welcome to the about page!'); }); app.get('/contact', (req, res) => { res.send('Welcome to the contact page!'); }); app.listen(port, () => { console.log(`Server started on port ${port}`); }); ``` Restart the web server by executing `node app.js`, and verify that the new routes are working by navigating to the corresponding URLs in your web browser. **Conclusion:** In this lab topic, you set up a Node.js and Express.js development environment, created a simple web server, and defined basic routes using Express.js. You have gained practical experience in building web applications with Node.js and Express.js. Keep practicing and experimenting with different routes and web application scenarios. **Leave a comment or ask for help:** If you have any questions or concerns about this topic or would like further clarification on any of the steps, please leave a comment below. **Additional Resources:** * [Express.js Documentation](https://expressjs.com/en/4x/api.html) * [Node.js Documentation](https://nodejs.org/en/docs/) **Proceed to the next topic:** In the next topic, we will cover "Understanding routing in Express.js (parameterized routes, query strings)" from the Routing and Middleware section. Get ready to dive deeper into Express.js routing concepts!