The npm package looks for exports in the index.js file located in src/index.js
The format of this is:
.env file contents for deployed backend: REACT_APP_BACKEND_BASE_URL=https://ocean-commotion-backend.herokuapp.com
.env file contents for local backend: REACT_APP_BACKEND_BASE_URL=http://localhost:3001
Note: Remember to restart the app when the .env file is changed
Compile the entire src directory and output it to the lib directory by using either --out-dir or -d. This doesn't overwrite any other files or directories in lib.
Source: https://babeljs.io/docs/en/babel-cli