Debug a Node.js / Typescript with Visual Studio Code

  • docker
  • nodejs
  • typescript
  • vscode

Publié le 2021-10-01

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I always have trouble using the VSCode debugger when I want to put breakpoints in a script or a Node.js application. In some cases I even end up putting console.log.

So I made this post which gives the configuration for the cases I encountered.

Node.js

The case where you just have Node.js and that's it. Let's say you have a script named ./src/index.js.`

Attach

Run your script with

node --inspect src/index.js
{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Node.js - Attach",
      "port": 9229,
      "request": "attach",
      "cwd": "${workspaceRoot}",
      "sourceMaps": true,
      "skipFiles": ["<node_internals>/**"],
      "type": "node"
    }
  ]
}

Launch

Use VScode to run script

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Node.js - Run & Debug",
      "args": ["${workspaceFolder}/src/index.js"],
      "sourceMaps": true,
      "cwd": "${workspaceRoot}",
      "protocol": "inspector"
    }
  ]
}

Node.js with Docker

The container must give --inspect=0.0.0.0:9229 flag to node:

# docker-compose.yml
version: "3.3"
services:
  node:
    image: node:16-slim
    working_dir: /usr/src/app
    command: node --inspect=0.0.0.0:9229 src/index.js
    volumes:
      - ./:/usr/src/app
    ports:
      - 9229:9229

The VSCode configuration must specify localRoot and remoteRoot to map between remote and local files.

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Node.js & Docker - Attach",
      "port": 9229,
      "request": "attach",
      "cwd": "${workspaceRoot}",
      "localRoot": "${workspaceFolder}",
      "remoteRoot": "/usr/src/app",
      "sourceMaps": true,
      "skipFiles": ["<node_internals>/**"],
      "type": "node"
    }
  ]
}

Typescript with ts-node

Let's complicate stuffs with Typescript:

npm init -y
npm install --save-dev ts-node typescript
npx tsc --init

Attach

node -r ts-node/register --inspect src/index.ts

The rest is identical to the example with Node.js

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "ts-node - Attach",
      "port": 9229,
      "request": "attach",
      "cwd": "${workspaceRoot}",
      "sourceMaps": true,
      "skipFiles": ["<node_internals>/**"],
      "type": "node"
    }
  ]
}

Launch

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "ts-node - Launch & debug",
      "type": "node",
      "request": "launch",
      "runtimeArgs": ["-r", "ts-node/register"],
      "runtimeExecutable": "node",
      "args": ["--inspect", "${workspaceFolder}/src/index.ts"],
      "cwd": "${workspaceRoot}",
      "skipFiles": ["<node_internals>/**", "node_modules/**"]
    }
  ]
}

Typescript with ts-node inside a Docker container

Just copy the above command into the docker-compose definition

# docker-compose.yml
version: "3.3"
services:
  ts-node:
    image: node:16-slim
    working_dir: /usr/src/app
    command: node -r ts-node/register --inspect=0.0.0.0:9229 src/index.ts
    volumes:
      - ./:/usr/src/app
    ports:
      - 9229:9229

And the configuration is similar to the previous example with Docker

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "ts-node & Docker - Attach",
      "port": 9229,
      "request": "attach",
      "cwd": "${workspaceRoot}",
      "localRoot": "${workspaceFolder}",
      "remoteRoot": "/usr/src/app",
      "sourceMaps": true,
      "skipFiles": ["<node_internals>/**"],
      "type": "node"
    }
  ]
}

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