fetch-rx.js

function fetchRx(url, options) {
  const controller = new AbortController();
  const { signal } = controller;
  return Observable.create(observer => {
    fetch(url, { signal, ...options })
      .then(x => observer.next(x))
      .catch(x => observer.error(x))
      .finally(() => observer.complete())
    return () => controller.abort();
  });
}