Debugging Node.js Applications: Using the Built-in Debugger

Learn how to effectively debug your Node.js applications using the built-in debugger. This tutorial explains how to start the debugger, use common debugging commands (continue, next, step, pause), inspect variables, and troubleshoot your JavaScript code.

Debugging Node.js Applications

Introduction

Node.js includes a built-in debugger that uses a simple TCP-based protocol. This debugger allows you to step through your JavaScript code, inspect variables, and identify errors. This tutorial explains how to use the Node.js debugger.

Starting the Debugger

To start the debugger, use the `node debug` command followed by the name of your JavaScript file:

node debug script.js 

Replace `script.js` with the actual path to your JavaScript file. If you omit the filename, the debugger will start in interactive mode, prompting for commands.

Example

To debug a file named `main.js`, you would run:

node debug main.js

Handling Errors

If you provide an incorrect file path or have errors in your JavaScript code, the debugger will output error messages. For example, if `main.js` isn't in the current directory or contains syntax errors, the output would indicate the problem.

Debugger Commands

(A table listing common Node.js debugger commands—like `cont`, `next`, `step`, `backtrace`, `repl`—would be included here. This section should explain briefly what each command does.)

Conclusion

The built-in Node.js debugger is a valuable tool for identifying and fixing errors in your JavaScript code. It provides a simple way to interact with your running application during debugging.