Facebook provides a create-react-app command to build react apps. When we run npm run build, we see output in /build folder.
Create-react-app Version 2+ answer
For recent (> v2) versions of create-react-app (and possible older as well), add the following line to your package.json, then rebuild.
"homepage": "./"
You should now see the build/index.html will have relative links ./static/... instead of links to the server root: /static/....