Previous

Node.js Debugger

The Node.js debugger is a built-in tool that helps developers identify and fix issues in their code. It allows for step-by-step execution, inspection of variables, and setting breakpoints, providing an effective way to debug Node.js applications.

 

Key Features of the Debugger

  1. Enables step-by-step execution of code for error analysis.
  2. Allows setting breakpoints to pause execution at specific lines.
  3. Provides inspection of variable values and call stack during debugging.
  4. Works seamlessly with modern IDEs and the Node.js command line.

 

How to Use the Debugger

  1. Command Line Debugging: Use the node inspect command to start debugging.
  2. IDE Integration: Popular IDEs like Visual Studio Code offer integrated debugging tools.
  3. Breakpoints: Pause execution at specific lines using debugger statements or IDE tools.

 

Example Code

Using the Debugger in the Command Line

// save this as app.js  
function add(a, b) {  
  return a + b;  
}  

function main() {  
  const result = add(5, 10);  
  console.log('Result:', result);  
}  

main();

To debug:

Run the application in inspect mode:

node inspect app.js

Use the n command to step to the next line or c to continue.

Inspect variables using commands like repl.

Using Debugger Statement

function multiply(a, b) {  
  debugger; // Execution pauses here  
  return a * b;  
}  

console.log(multiply(4, 5));

Run the code in debug mode:

node inspect app.js

The execution will pause at the debugger statement.

Debugging in Visual Studio Code

  1. Open the project in VS Code.
  2. Go to the "Run and Debug" panel and add a new launch configuration.
  3. Set breakpoints by clicking on the left margin of the editor.
  4. Start debugging by clicking the green "Start Debugging" button.

 

Summary

The Node.js debugger is an essential tool for identifying and fixing issues in your code. Whether used through the command line, IDE integration, or with debugger statements, it provides an efficient way to trace code execution and inspect variable states, streamlining the debugging process.

Previous