This is a slight improvement over https://github.com/TotallyInformation/node-red-contrib-uibuilder/wiki/Example:-ReactJS .

clone example and install dependencies

# assuming 
cd ~/.node-red/uibuilder
git clone https://github.com/gaillarddamien/uibuilder-react-example.git
cd uibuilder-react-example
npm install

production build

npm run build

It has been built under ~/.node-red/uibuilder/uibuilder-react-example/dist (see .env). It is no longer needed to copy or symlink stuff.

You can now open http://localhost:1880/uibuilder-react-example

development server

npm run start

Open http://localhost:3000/uibuilder-react-example

Note this works because package.json:proxy resolves to the node-red instance (by default http://localhost:1880).