Functional Heroku production build (frontend + backend) at address: https://tranquil-everglades-28442.herokuapp.com/
This is a React app representing a phonebook that includes a production build of the frontend, integrated with an Express backend.
Users can add new contacts to their phonebook, and are presented with a colourful message indicating success.
Users can search (case-indifferent) for contacts in their phonebook, and the app will re-render to display only contacts with names that match the search string.
Users can also update the number of a contact that already exists (they're asked if they're sure first), and are presented with a colourful message indicating success once the operation is completed.
Lastly, edge cases where the user opens the app and interacts with it in separate windows are handled. If a user deletes a contact in one window, and then attempts to change the number of the recently-deleted contact in another window, they are presented with a styled error message indicating that the contact has already been removed from their phonebook.