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Debug your Node.js app with Chrome DevTools

bennycode profile image Benny Neugebauer Updated on ・2 min read

You can use Chrome's DevTools to debug Node.js applications. It's called remote debugging and can be started from Google Chrome's internal website.

Setup your Node.js app for debugging

To inspect your Node.js app with Google Chrome DevTools, you have to make it a remote target. This can be done by using the --inspect flag when starting the node process:

  • node --inspect ./dist/app.js

Use Chrome DevTools

Once your Node.js app is registered as remote target and listening for debuggers, you can open the webpage chrome://inspect/#devices in Google Chrome to see the dedicated DevTools for Node.

Set IP and Port

By default, the DevTools try to discover targets on "127.0.0.1:9229". You can change the host and port. Make sure that your Node.js process is listening to it. You can point Node.js to a specific IP and Port by running:

  • node --inspect=127.0.0.1:9200 ./dist/app.js

If you want to allow external connections (from the public internet) you have to bind the debugging interface to IP/Host "0.0.0.0".

Use CLI Debugger

If you want to run debugging entirely in the CLI, you can start your app with:

  • node inspect ./dist/app.js (note the missing hyphens!)

Be aware that the Node.js inspector supports breakpoints but is not a full-featured debugger. If you want to continue from a breakpoint (set with the debugger statement), you have to enter cont (continue) within the CLI.

Pause Debugging

When your app has a heavy initialization, you may want to pause your app until the debugger is attached. This can be done by using the flag --inspect-brk, which sets a break before running your code. You can use your remote debugger (i.e. Chrome DevTools) to unpause the debugging process.

TypeScript Debugging Setup

If you want to use Node's debugger for TypeScript code, you will have to compile your Node.js app to JavaScript. Make sure that the compiler option "sourceMap" in "tsconfig.json" is set to true in order to get source map support.

  1. Run npx tsc to compile your TypeScript app to JavaScript
  2. Run node --inspect ./dist/app.js to start your compiled code in watch mode for debuggers

When you are using ts-node, you can directly call:

  • node --inspect -r ts-node/register ./src/app.ts

Video Tutorial

The video below, will help you with the Node.js debugging setup:

Following the YouTube link, you will also find the timeline for each chapter:

Want more?

If you liked this post, then I invite you to take a look at the YouTube channel of TypeScript TV. Together with friends, I am publishing videos on best practices with TypeScript whenever we find something exciting.

Discussion (4)

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vjnvisakh profile image
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Andrew Baisden

Great post!

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deexter profile image
deexter

Thank you for the post, could you provide how to connect debugger with IDE like webstorm?

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zer0 profile image
zer0

There is an official documentation for it
jetbrains.com/help/webstorm/runnin...