Connecting the frontend and the backend
To make the frontend app communicate with the backend app, we'll need to enable cross-domain communication on the backend so that the traffic from the frontend can go through to the backend. This can easily be done with the Cross-Origin Resource Sharing (CORS) middleware that we will add to our Express app.
To work with SQLite databases, we use the sqlite3 library, which lets us manipulate the SQLite database within the Node.js apps. We can make queries and run SQL commands to insert or remove data from our database.
Additionally, we will have simple authentication for the admin frontend. We will check the username and password for the admin login, and if it's valid, we can issue a token and send it to the frontend. Then, the frontend will use the token, which is stored in the header, to check whether the request can be made from the frontend. We add authentication for the admin-only routes only, so we only need to check the token...
