Bootstraped the repo using this tutorial: https://blog.logrocket.com/how-to-set-up-node-typescript-express/

mkdir jaipur-backend
cd jaipur-backend
npm init
npm install express dotenv
npm i -D typescript @types/express @types/node
npx tsc --init
# "outDir": "./dist" in tsconfig.json
# npm scripts in package.json
# "build": "npx tsc",
# "start": "node dist/index.js",
# "dev": "concurrently \"npx tsc --watch\" \"nodemon -q dist/index.js\""

This is the backend of the jaipur card game located in this repository: https://github.com/mpsido/jaipur. Please have a look at the README.md of the frontend repo to understand what the card game is about.

The backend serves a REST API on port 3000. The API functions are defined in index.ts.

The backend listens to websocket on port 3001. The websockets messages are defined in websocket.ts.

In order to represent the state of every game room the backend implements an "in memory" storage whose code is in store.ts.

The game logic is coded in game.ts. You can see the definition of the GameState structure that is exchanged between the frontend and the backend in the websocket messages.