How to move useEffect from component to custom hook

Question

I have multiple components with the same useEffect code.

fucntion MyComponent1 (props) {

 const {
        handleApiCall,
        data,
        isLoading,
        isError,
        isSuccess,
  } = useCustomAsyncHook();

 React.useEffect(() => {
   if (isSuccess && !isEmpty(data)) {
      setSnackbar({
        show: false,
        message: '',
      });
      dispatch({
        type: ACTION_TYPES.UPDATE_METADATA,
        payload: { data },
      });
    }
 }, [data, isSuccess, setSnackbar]);

 const onSave = () => {
     handleApiCall()
 }

 return (
   <button onClick={onSave}> Save </button>
 )

}

I have this useEffect hook code repeating in multiple components. I just want to move this useEffect hook into custom hook so that I need not repeat it in multiple components.

const useMetadataUpdate = ({ data, isSuccess, setSnackbar, dispatch }) => {
    React.useEffect(() => {
        if (isSuccess && !isEmpty(data)) {
            setSnackbar({
                show: false,
                message: '',
            });
            dispatch({
                type: ACTION_TYPES.UPDATE_METADATA,
                payload: { data },
            });
        }
    }, [data, isSuccess, setSnackbar, dispatch]);
};

fucntion MyComponet1 (props) {
   const {
        handleApiCall,
        data,
        isLoading,
        isError,
        isSuccess,
  } = useCustomAsyncHook();

  useMetadataUpdate({ data, isSuccess, setSnackbar, dispatch });

  const onSave = () => {
     handleApiCall()
 }

 return (
   <button onClick={onSave}> Save </button>
 ) 
}

Refactoring useEffect to a separate function works. I can't find documentation explicitly stating a hook needs to return anything, however, I cannot find an example of a hook not returning something. Can someone advise on if this approach is correct?

Answer 1

The current issue as I can see here is that you have 3 functions namely isEmpty , setSnackbar , and dispatch tightly coupled to your components here. This restricts you from directly moving this useEffect to your custom hook. The best solution that I can think of right now is moving these functions to a custom hook(you can combine this with context API as well). After that, you can do the following in your custom hook

const useCustomAsyncHook = () => {
  // code to fetch dependenices like `data`, `isSuccess` goes here

  const { setSnackbar, isEmpty, dispatch } = useAnotherCustomHook();

  React.useEffect(() => {
    if (isSuccess && !isEmpty(data)) {
       setSnackbar({
         show: false,
         message: '',
       });
       dispatch({
         type: ACTION_TYPES.UPDATE_METADATA,
         payload: { data },
       });
     }
  }, [data, isSuccess, setSnackbar]);
};

Answer 2

To clean up your component, you can move useEffect to a custom hook that contains the same logic as the original.

For example

// useCodeSelection.js
...
export const useCodeSelection = () => {
    useEffect(() => {
        console.log('useCodeSelection')
    }
}
...

Then inside your component just call it after you import it, like:

...
useCodeSelection()
...