Simple Relay environment with auth header

environment.js

// Reference: https://relay.dev/docs/guides/network-layer

import { Environment, Network, RecordSource, Store } from 'relay-runtime';

// Function to get the authentication token
export const getToken = () => {
  return localStorage.getItem('authentication_token');
};

// Define a function that fetches the results of an operation (query/mutation/etc)
// and returns its results as a Promise:
function fetchQuery(operation, variables, cacheConfig, uploadables) {
  const token = getToken();

  return fetch('/graphql', {
    method: 'POST',
    headers: {
      // Add authentication and other headers here
      authorization: token ? `Bearer ${token}` : null,
      'content-type': 'application/json',
    },
    body: JSON.stringify({
      query: operation.text, // GraphQL text from input
      variables,
    }),
  }).then((response) => {
    return response.json();
  });
}

// Create a network layer from the fetch function
const network = Network.create(fetchQuery);
const store = new Store(new RecordSource());

const environment = new Environment({
  network,
  store,
  // ... other options
});

export default environment;