Reaccionar ambiente
create .env file in root directory
in this file create envirement variable starting with REACT_APP..
example : REACT_APP_BACKEND_URL = http://localhost:5000/
call it in your react app like this process.env.REACT_APP_BACKEND_URL
N.B if your app is running and you wanna add those lines you must shutdown
the app and run it again it will work as charm
Mushy Magpie