npx create-react-app 내 앱 이름 --template typescript npm i --save-dev @유형/styled-components npm i styled-components // index에서 root에러가 난다면 const root = ReactDOM.createRoot(document.getElementById('root') as HTMLElement) //이렇게 수정 interface : object shape(객체모양)을 TypeScript에게 설명해주는 개념 interface PlayerShape { name: string age: number } const sayHello = (playerObj: PlayerShape) => `Hello ${playerObj.nam..