create react project

use create-react-app to start building a new single-page application

npx create-react-app react-demo
cd react-demo
npm start

if something is already running on port 3000, follow below step, modify start code in package.json

// windows
set PORT=5000 && react-scripts start
//mac
PORT=5000 react-scripts start

have a reference: https://github.com/vincentzyc/notes/issues/2