**Course Title:** Mastering Node.js: Building Scalable Web Applications **Section Title:** Error Handling and Debugging **Topic:** Debugging Node.js applications with built-in tools and Visual Studio Code In this topic, we will explore the built-in tools and Visual Studio Code features that can help you debug your Node.js applications. Debugging is an essential part of the development process, and understanding how to use these tools will make you a more efficient and effective developer. **Built-in Node.js Debugging Tools** Node.js provides several built-in tools for debugging, including: 1. **Node Inspector**: A built-in debugger that allows you to inspect and debug your Node.js applications. 2. **V8 Inspector**: A built-in debugger that allows you to inspect and debug your Node.js applications. 3. **Node.js CLI**: The Node.js command-line interface provides several debugging options, including `--inspect` and `--debug`. **Using Node Inspector** Node Inspector is a built-in debugger that allows you to inspect and debug your Node.js applications. To use Node Inspector, follow these steps: 1. Start your Node.js application with the `--inspect` flag: `node --inspect app.js` 2. Open a web browser and navigate to `http://localhost:5858` 3. Click on the "Inspect" button to open the Node Inspector interface **Using V8 Inspector** V8 Inspector is a built-in debugger that allows you to inspect and debug your Node.js applications. To use V8 Inspector, follow these steps: 1. Start your Node.js application with the `--inspect` flag: `node --inspect app.js` 2. Open a web browser and navigate to `http://localhost:5858` 3. Click on the "Inspect" button to open the V8 Inspector interface **Using Node.js CLI Debugging Options** The Node.js CLI provides several debugging options, including `--inspect` and `--debug`. To use these options, follow these steps: 1. Start your Node.js application with the `--inspect` flag: `node --inspect app.js` 2. Start your Node.js application with the `--debug` flag: `node --debug app.js` **Visual Studio Code Debugging** Visual Studio Code (VS Code) is a popular code editor that provides a built-in debugger for Node.js applications. To use the VS Code debugger, follow these steps: 1. Install the Node.js extension for VS Code 2. Create a launch configuration file (e.g. `launch.json`) 3. Start your Node.js application with the `--inspect` flag: `node --inspect app.js` 4. Open the VS Code debugger by clicking on the "Run" button or pressing F5 **Key Concepts** * **Breakpoints**: A breakpoint is a point in your code where the debugger will pause execution. * **Variables**: Variables are values that are stored in memory. * **Stack**: The stack is a data structure that stores the current state of your application. * **Call stack**: The call stack is a data structure that stores the current state of your application's function calls. **Practical Takeaways** * Use the built-in Node.js debugging tools (Node Inspector, V8 Inspector, and Node.js CLI) to debug your Node.js applications. * Use Visual Studio Code to debug your Node.js applications. * Understand the key concepts of breakpoints, variables, stack, and call stack. * Use the VS Code debugger to step through your code, set breakpoints, and inspect variables. **Exercise** * Create a Node.js application that uses the `--inspect` flag to start the debugger. * Use the VS Code debugger to step through your code, set breakpoints, and inspect variables. * Use the Node Inspector to inspect and debug your Node.js application. **Additional Resources** * Node.js documentation: [https://nodejs.org/en/docs/](https://nodejs.org/en/docs/) * Visual Studio Code documentation: [https://code.visualstudio.com/docs](https://code.visualstudio.com/docs) * Node.js Inspector documentation: [https://nodejs.org/en/docs/guides/debugging-getting-started/](https://nodejs.org/en/docs/guides/debugging-getting-started/) **Leave a comment or ask for help if you have any questions or need further clarification on any of the topics covered in this topic.**