crate-react-app react-login
cd react-login
cnpm i
npm run eject
npm run start
localhost:3000
升级 react react-dom 包 16.8 npm update
https://reacttraining.com/react-router/web/example/route-config
react-router core api Router route switch , no dom api link BrowserRouter hashRouter BrowserRouter hashRouter # hash
未处理的 UI 未处理 validation 代码form component 复用度还是不高