React app fetch request from IP address if no domain name is available

Question

I have written a React application (React+Vite) which makes some fetch requests.

Here is an example:

const fetchRows = async () => {
  let rows = [];
  const response = await axios.post(
    'http://localhost:81/api/get_rows',
    {}
  );
  rows.push(response.data['rows']);
  return rows;
};

It doesn't matter too much what this code does. The important part is the hostname used in the request, in this case the POST request is directed to localhost:81.

This works fine during development where the same machine is used to host the backend webserver, the NodeJS/React/Vite development environment/server and the web browser use to test the whole system.

Unsurprisingly, this no longer works in production, when my application and backend logic is deployed to a server on the cloud, and I am trying to interact with it from some other machine.

I do not have a domain name setup for this system. I can create one if absolutly necessary, however I would prefer to just hardcode the ip address in place of localhost rather than go and buy a domain name.

• I know that domain names are not expensive, I just don't want to configure it as this is for a demonstration project and it doesn't have any particularly important application other than as a demo.

Is there a relatively easy way to write some React code which uses an ip address in place of localhost without resorting to hardcoding the address which obviously isn't a great solution?

eg: Is there a React or JavaScript function which can ask the host machine what its ip address is?

This might not be so easy since any machine has multiple ip addresses. (127.0.0.1 being an obvious example that all Linux hosts have.)

Any suggestions welcome. If buying a domain is easier, I'll just do that.