React - Debounce useEffect-CodePudding

I have created a debounced method inside my react component.

const [count, setCount] = useState(0);

const lazyLog = useCallback(
  _.debounce(() => { console.log(count) }, 5000),
  [count]
);

and I am calling it inside a useEffect, every time count is updated:

useEffect(() => {
  lazyLog();
}, [count])

The problem I am experiencing is that, as the lazyLog method is recreated on each render, the debounce functionality is not applied correctly.

You can check this snack to test the code.

How can I fix the code? As the useCallback must include the dependency... I don't find any easy way to handle this... any ideas?

CodePudding user response：

State is stale as it's not included in the dependency array of useCallback. Now if you add that the deBounce will not work.

Solution is to use a ref & hold a copy of the state in that. Then use that in the debounce. (Codesandbox)

Also - [count] should be [] in useCallback.

const refValue = useRef(count);

const lazyLog = useCallback(
    _.debounce(() => {
      console.log("debounce", refValue.current);
    }, 2000),
    [] // empty
  );

  useEffect(() => {
    refValue.current = count;
    lazyLog();
  }, [count]);

CodePudding user response：

I don't like the useDebounce hook, described in the comments, at all, because I want to debounce the callback and not the value.

I think that, in order to avoid problem with the stale state, I will pass the counter as argument, instead of consuming it directly from my state.

export default function App() {
  const [count, setCount] = useState(0);

  const lazyLog = useCallback(
    _.debounce((count) => { console.log(count); }, 5000),
    []
  );

  useEffect(() => {
    lazyLog(count);
  }, [count])

  return (
    <View>
      <Text onPress={() => setCount(prevCount => prevCount   1)}>
        Increase
      </Text>
    </View>
  );
}

https://snack.expo.dev/67W9HnsRD

Not as clean as it could be but works fine with some minimal changes.