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Node.js Debugging

Debugging Node.js

Node.js debugging uses console and --inspect with Chrome DevTools.

Introduction to Node.js Debugging

Debugging is a crucial skill for any developer, and Node.js offers powerful tools to help identify and fix problems in your code. This guide will focus on two primary methods for debugging Node.js applications: using the console object and the --inspect flag with Chrome DevTools.

Using the Console for Debugging

The console object in Node.js provides simple methods to output information to the terminal. This is often the first step in debugging, allowing you to check the values of variables and the flow of execution in your code.

Here are some commonly used console methods:

  • console.log() - Outputs a message to the console.
  • console.error() - Outputs an error message.
  • console.warn() - Outputs a warning message.
  • console.table() - Displays data as a table.

Debugging with --inspect and Chrome DevTools

The --inspect flag allows you to use the Chrome DevTools for a more interactive debugging experience. To start debugging, run your Node.js application with the --inspect flag.

Here's how you can do it:

After starting your application with the --inspect flag, open Chrome and navigate to chrome://inspect to access the DevTools. Click on 'Open dedicated DevTools for Node' to start debugging. You can set breakpoints, step through code, and inspect variables just like you would in a browser environment.

Setting Breakpoints in Chrome DevTools

Breakpoints allow you to pause the execution of your code at a specific line so you can examine the current state. To set a breakpoint, simply click on the line number in the Sources panel of Chrome DevTools.

Once the execution is paused, you can inspect the values of variables, evaluate expressions, and step through your code line by line.

Conclusion

Debugging is an essential part of development, and Node.js provides robust tools to assist in this process. By utilizing the console object and the --inspect flag with Chrome DevTools, you can effectively identify and resolve issues in your applications. With practice, these tools will become an integral part of your debugging workflow.

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