1npx create-react-app app-name --template typescript
2# or using yarn
3yarn create react-app app-name --template typescript
1npm install --save typescript @types/node @types/react @types/react-dom @types/jest
2# or
3yarn add typescript @types/node @types/react @types/react-dom @types/jest
1yarn add typescript @types/node @types/react @types/react-dom @types/jest --dev
2#...then rename your .js files to .tsx