make react app

1npx create-react-app my-app
2cd my-app
3npm start

1npx create-react-app app-name
2cd app-name
3npm start

1npx create-react-app my-app
2cd my-app
3npm start
4//Note:npx on the first line is not a typo — 
5//it’s a package runner tool that comes with npm 5.2+.