Daily Share: A Custom React Hook that handles duplicate API call

let isCalling = new Map(); // This can be replace by some global state. I use this for the sake of simplicity.
function useFetch(url) {
  const [data, setData] = useState("");
  useEffect(() => {
    let isThisAPICalling = isCalling.get(url);
    if (!isThisAPICalling) {
      console.log("new");
      isThisAPICalling = fetch(url).then((response) => response.json());
      isCalling.set(url, isThisAPICalling);
      // The body can only be parsed once.
    }
    isThisAPICalling.then((json) => {
      console.log("done");
      console.log(json.title);
      isCalling.set(url, null);
      setData(json.title);
    });
  }, []);
  return data;
}