Node.js and TypeScript Setup

TypeScript in Node.js requires a bit of configuration — Node.js doesn’t understand TypeScript natively. This lesson sets up the project structure used for the Bulletin API.

Two approaches

Option 1: Compile first — Use tsc to compile TypeScript to JavaScript, then run the JavaScript. Good for production builds.

Option 2: tsx (recommended for development) — tsx is a tool that runs TypeScript directly without a separate compile step. Faster for development.

This course uses tsx for development and tsc for production builds.

Project setup

mkdir bulletin-api
cd bulletin-api
npm init -y

Install TypeScript and tsx:

npm install --save-dev typescript tsx @types/node

tsconfig.json for Node.js

npx tsc --init

Update tsconfig.json with Node.js-appropriate settings:

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "outDir": "./dist",
    "rootDir": "./src",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist"]
}

Key settings:

• "module": "NodeNext" — use Node.js’s native ES module resolution
• "outDir": "./dist" — compiled output goes here
• "rootDir": "./src" — source files live here
• "strict": true — full TypeScript strictness

Project structure

bulletin-api/
├── src/
│   ├── index.ts          ← entry point
│   ├── routes/           ← Express route handlers
│   ├── middleware/        ← custom middleware
│   ├── db/               ← database setup and queries
│   └── types/            ← shared TypeScript types
├── tsconfig.json
└── package.json

npm scripts

Update package.json:

{
  "scripts": {
    "dev": "tsx watch src/index.ts",
    "build": "tsc",
    "start": "node dist/index.js"
  }
}

• npm run dev — runs with tsx watch (auto-restarts on file changes, like Nodemon)
• npm run build — compiles TypeScript to dist/
• npm start — runs the compiled JavaScript

Your first TypeScript server file

src/index.ts

const message: string = 'Bulletin API starting...'
console.log(message)
console.log('Node.js version:', process.version)

Run it:

npm run dev

You should see the output. Change the message and watch it restart automatically.

Exercise

1. Follow the setup above to create a bulletin-api project directory.
2. Install the dependencies and configure tsconfig.json.
3. Create src/index.ts with a typed variable and run npm run dev.
4. Change the message in the file — confirm the server restarts and shows the new output.

Recap

• tsx runs TypeScript files directly — no separate compile step needed during development.
• tsconfig.json with "module": "NodeNext" is the correct setup for modern Node.js.
• Source goes in src/, compiled output goes in dist/.
• npm run dev uses tsx watch for auto-restart; npm start runs the compiled build.