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Eduardo Rabelo
Eduardo Rabelo

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Node.js with TypeScript, Debug inside VSCode and Nodemon

Setup Node.js and TypeScript can be straightforward. Our daily work sometimes involves a lot of debugging and we also need to reload our server.

Let's walk through how we can setup Node.js with TypeScript + Nodemon + Debug inside VSCode (as an extra, you can debug it inside Chrome DevTools).

Less talk, more code! πŸ€“

πŸ“¦ Dependencies and Configurations

$ mkdir devto-node-typescript
$ cd $_

Adding our dependencies:

$ yarn init -y
$ yarn add @types/express@^4.16.1 express@^4.16.4 nodemon@^1.18.10 ts-node@^8.0.3 typescript@^3.3.4000

Here is our dependencies list:

  • @types/express@^4.16.1
  • express@^4.16.4
  • nodemon@^1.18.10
  • ts-node@^8.0.3
  • typescript@^3.3.4000

Now, let's create our nodemon.json file:

$ touch nodemon.json
$ vim $_

And paste the following:

{
  "restartable": "rs",
  "ignore": [".git", "node_modules/**/node_modules"],
  "verbose": true,
  "execMap": { // [A]
    "ts": "node --require ts-node/register"
  },
  "watch": ["src/"],
  "env": {
    "NODE_ENV": "development"
  },
  "ext": "js,json,ts"
}
  • // [A]: Here we're saying to nodemon: "Hey nodemon, if we run "nodemon" with a ".ts" file, please, use this line to execute the file". Because of that, now we can do nodemon server.ts and it will use ts-node to compile our file.

To learn more about Nodemon config, you can check the sample in their repository

Now, let's create our tsconfig.json file:

$ touch tsconfig.json
$ vim $_

And use:

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "outDir": "./dist",

    "strict": true,

    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,

    "esModuleInterop": true
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "**/*.test.ts"]
}

There's no much difference from the default config (e.g. when you run tsc --init)

We are almost there, let's create a npm script to start our future server:

// ...

"scripts": {
  "dev": "nodemon src/entry.ts"
}

// ...

Now, it's time to create our server.

πŸ’» Writing our server and some routes

As we saw in our nodemon and npm scripts configuration, we need to create a folder called src and file called entry.ts:

$ mkdir src
$ cd $_
$ touch entry.ts
$ vim $_

Let's write the following:

import express from 'express';

const server = express();

server.use('/_healthcheck', (_req, res) => {
  res.status(200).json({ uptime: process.uptime() });
});

server.listen(4004, () => { console.log('Running at localhost:4004') })

Now we can run:

$ yarn dev

And see our Node.js with TypeScript + Nodemon server running:

Fantastic! πŸŽ‰

But wait... one important part is missing, how I can debug this thing? 😱

πŸ“Š Attaching Debug configuration to our project

Using nodemon we simply pass the --inspect flag to make our Node process debuggable. Let's create a new npm script for that:

// ...

"scripts": {
  // ...
  "dev:debug": "nodemon --inspect src/entry.ts"
}

// ...

If we run:

$ yarn dev:debug

We can see the debug option in our logs:

Great! Let's create our VSCode configuration:

$ mkdir .vscode
$ cd $_
$ touch launch.json
$ vim $_

And paste the following:

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "attach",
      "name": "Node: Nodemon",
      "processId": "${command:PickProcess}",
      "restart": true,
      "protocol": "inspector"
    }
  ]
}

This configuration is based in one of Microsoft Recipes for VSCode.

Let's open our VSCode editor and do go the "Debug" panel:

With our yarn dev:debug running, let's press the green arrow shown in the screenshot above.

First, we need to select the process pointing to our server:

After we select it, we can see a floating debug panel and some UI changes:

Now you can add a breakpoint in your code and have fun inside your editor with server reload by nodemon:

Delightful experience! ❀️ πŸŽ‰ 😎

🌐 Extra: It also works in Google Chrome DevTools

Yep. We can use the following steps:

  • Navigate to chrome://inspect

  • Click inspect inside Remote Target section pointing to your server and have fund debugging your server using Chrome DevTools:

NOTE: I tried to use "Open dedicated DevTools for Node" option, but it doesn't work well :( If you know how to make it work, share with us!

β˜•οΈ I want it all and more!

What about tests? Folder structure? There's a default project?

Say no more! For my personal use, I've a small non-opinionated default project in:

https://github.com/oieduardorabelo/node-typescript

You will find:

  • Node.js + TypeScript
  • Jest
  • Nodemon

Feel free to fork, contribute and use!

Happy coding! πŸ™Œ

Top comments (10)

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sirluis profile image
Luis Henrique

Nice, thanks for sharing.
For anyone having problems with vscode not showing the node process, do this:

  • Specify a port to the debbuger process on package.json nodemon script: nodemon --inspect:9229 src/server.ts
  • Replace this line: `"processId": "${command:PickProcess}" with: "port": 9229 inside the launch.json file. Thats all.
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briancodes profile image
Brian • Edited

This is very handy to know, and I've used some of this to debug Angular Universal server side code.

In the GitHub project you linked, I notice you use webpack for production build. Is it necessary to use webpack when using TypeScript server side?

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oieduardorabelo profile image
Eduardo Rabelo

oh, thanks mate! didn't noticed it, it should be in a separated branch, not master.

it is not necessary, it is my personal approach to always bundle my server-side code, inspired by github.com/jaredpalmer/backpack

i'll update my master branch

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kspence profile image
Kevin

Exactly what I was looking for... Thank you Eduardo!

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mausconi profile image
nizar

Thanks for sharing Eduardo.

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spock123 profile image
Lars Rye Jeppesen

Thank you for doing God's work. This is amazing.
My biggest issue has been getting nodemon working with path aliases defined in tsconfig.json

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dtx92 profile image
DTX-92

Awesome, thanks
But can you please explain, how do I add support for module aliases?

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oieduardorabelo profile image
Eduardo Rabelo • Edited

thanks for your comment,

absolutely, for this setup it would be a little bit tricky, because:

  • we are not using a bundler (e.g. webpack, rollup etc)
  • if you use a module alias, the output Node.js code (e.g. inside "dist/*.js"), will have the aliased path, since TypeScript does not replace the import path string
  • because of that, you will need to maintain some kind of module alias resolution in the prod version for Node.js only (e.g. you need to start your server with a module alias solution)
  • we also need to keep mappings for Jest, because Jest doesn't use TypeScript module resolution

let's put the production scenario above aside, and focus on "dev" only, we can do:

let's clone the repo:

git clone https://github.com/oieduardorabelo/node-typescript
cd node-typescript
npm install
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and install tsconfig-paths

npm install tsconfig-paths
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inside our tsconfig.json we can define baseUrl and paths:

{
  "compilerOptions": {
     ...
    "baseUrl": ".",
    "paths": {
      "#domains/*": ["src/domains/*"]
    }
  },
  ...
}
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now we can use the alias #domains in any file, let's update server.ts:

...
import bookRoutes from '#domains/book/routes';
import reviewRoutes from '#domains/review/routes';

const server = express();
...
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now, let's register the module alias in our nodemon.json:

{
  ...
  "execMap": {
    "ts": "node --require ts-node/register --require tsconfig-paths/register"
  },
  ...
}
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now we can start the server with aliases:

npm run dev
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and it should work as before, but with aliases!

now, for the Jest mappings, you need to keep the same mappings from tsconfig.json but in the Jest syntax/config, we need to use moduleNameMapper. I'll add the Jest config in package.json for this example:

{
  ...
    "moduleNameMapper": {
      "^#domains/(.*)": "<rootDir>/src/domains/$1"
    }
  ...
}
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and now you can run your tests as before:

npm run test
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so far, so good.

now, for the production scenario, I do not have a good straight answer, because it requires a considerable amount of work to adapt it per project.

but thinking about the process to make it work, we could use something like module-alias

and we would need:

  • build the project with npm run build (e.g. typescript => node.js in dist/)
  • have a script to generate a package.json with module-alias inside dist/
  • add the same mappings from tsconfig.json inside dist/package.json but using module-alias syntax
  • run cd dist/ && npm install to install module-alias for production
  • and start your production server with node --require module-alias/register entry.js

phew, what a setup! ahahah

i hope it helped! πŸ‘‹

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pak11273 profile image
Isaac Pak

It would be nice if you could do an example with an async/await application on node and typescript.

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diass_le profile image
Leonardo Dias

Thank you, Eduardo!
This help me a lot.