Getting react unmounted hook error with Refresh Control

user_19294730 0
Viewed 26

When I use

const onRefresh = () => {
setRefreshing(true);

   setTimeout(() => {
     setRefreshing(false);
   }, 2000);
};

with RefreshControl in Scroll View and then I get change the page in the middle of refreshing, I get the error below. Normally I can fix this error with a useEffect hook but I can't seem to get it working in any way. Any ideas on how to fix this?

Warning: Can't perform a React state update on an unmounted component.
This is a no-op, but it indicates a memory leak in your application. 
To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.
uirefreshcontrol react-native react-hooks scrollview refresh
1 Answers

It's not an error, it's just a warning. I think you could still use a useEffect hook to cancel any running timers when the component unmounts. For convenience you use a React ref to hold a reference to the timeout.

Example:

const timerRef = React.useRef();

useEffect(() => {
  // return cleanup function to clear any running timeouts
  return () => clearTimeout(timerRef.current);
}, []);

const onRefresh = () => {
  setRefreshing(true);

  // save current timerId to ref
  timerRef.current = setTimeout(() => {
    setRefreshing(false);
  }, 2000);
};

I believe that this warning for state updates on unmounted components has been removed in React 18 since it often led to really poor code quality generally

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