longpolling_client.js

import { fetchUrl } from 'fetch';

const registerLongPolling = () => {
    let counter = 0;
    fetchUrl('http://localhost:3000/longpolling', (error, meta, body) => {
        if (error) {
          return;
        }

        if (counter > 4) {
          return;
        }

        setTimeout(() => {
          registerLongPolling();
          counter++;
        }, 1000);
    });
};