How to stop memory leak in useEffect hook react

Question

I am using Effect hook to fetch the datas from server and these data are passed to the react table there i have used the same api call to load the next set of datas from server.

Answer 1

With useEffect you can return a function that will be run on cleanup. So in your case, you'll want something like this:

useEffect(() => {
  let unmounted = false;

  setPageLoading(true);

  props
    .dispatch(fetchCourses())
    .then(() => {
      if (!unmounted) {
        setPageLoading(false);
      }
    })
    .catch((error: string) => {
      if (!unmounted) {
        toast.error(error);
        setPageLoading(false);
      }
    });

  return () => { unmounted = true };
}, []);

EDIT: if you need to have a call that's kicked off outside of useEffect, then it will still need to check an unmounted variable to tell whether it should skip the call to setState. That unmounted variable will be set by a useEffect, but now you need to go through some hurdles to make the variable accessible outside of the effect.

const Example = (props) => {
  const unmounted = useRef(false);
  useEffect(() => {
    return () => { unmounted.current = true }
  }, []);

  const setFilter = () => {
    // ...
    props.dispatch(fetchCourses()).then(() => {
      if (!unmounted.current) {
        setLoading(false);
      }
    })
  }

  // ...
  return (
    
  );
}