React – Updated prop in custom hook

I have a custom hook that gives me a certain percentage of the scroll. I takes the values from the state-management solution Zustand. I’m using it inside a component to update some styles on elements on the page.

The problem is that I only want to update these elements on a certain condition passed as prop of my component. And these conditions are not updated in my hook.

I don’t know how I should change it in order to get the updated condition.

import create from 'zustand'

const useStore = create(() => {
  scroll: 0
})

const useScroll = (callback: (scroll: number) => void): null => {
  const subscribe = useRef()

  useEffect(() => {
    if (subscribe & subscribe.current) {
      // Unsubscribe
      subscribe.current()
    }

    subscribe.current = useStore.subscribe(() => {
      callback(useStore.getState().scroll)
    })
  }, [subscribe])

  return null
}

const myComponent = (condition: Boolean) => {
  console.log(condition) // gives the updated value of the prop

  useScroll(() => {
    console.log(condition) // is not updated
  })
}

>Solution :

My guess is that you need to add the callback parameter to the list of properties useEffect is watching:

   useEffect(() => {
        ...
   }, [subscribe, callback])
   

That way, whenever the function callback changes because of a new condition, the useEffect will re-run.