Debug your Node.js app with Chrome DevTools
Tags: node, typescript, javascript, webdev
Published: 2021-03-26 17:25:02

---
title: Debug your Node.js app with Chrome DevTools
published: true
description: Learn how to use Chrome DevTools to debug Node.js applications with TypeScript
tags: nodejs, typescript, javascript, webdev
cover_image: https://images.unsplash.com/photo-1504292004442-f285299403fa
---

You can use Chrome's DevTools to debug Node.js applications. It's called [remote debugging](https://developers.google.com/web/tools/chrome-devtools/remote-debugging) and can be started from Google Chrome's internal website.
<!-- more -->
## 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](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](https://nodejs.org/api/debugger.html) 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
1. 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:

{% youtube bV-DHjmwuZ0 %}

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

- https://www.youtube.com/watch?v=bV-DHjmwuZ0

## Get connected 🔗

Please [follow me on Twitter](https://twitter.com/bennycode) or [subscribe to my YouTube channel](https://www.youtube.com/c/typescripttv) if you liked this post. I would love to hear from you what you are building. 🙂 Best, Benny