we continue with fetching data from useEffect and JSON!

You will need to run npm start (for localhost 3000 to run)

More importantly we need this to run:

npx JSON-server — watch data/data.json — port 8000

(if you copy and paste this, there should be two dashes in front of the watch and port, not just one dash, Medium autocorrects it.)

That starts up the JSON server for us.