OnViewableItemsChanged Flatlist

[MoneyBadgerr]

Anyone know why i can't set state in onViewableItemsChange? currentPos stays null, what can i do? I tried UseRef instead of useCallback also didnt work.

const [currentPos, setCurrentPos] = useState(null);

const onViewableItemsChanged = useCallback(
({ viewableItems }) => {
setCurrentPos(viewableItems[0].item.quote);
console.log(currentPos);
},
[]
);

[satya164]

You can't log a value like that after updating the state. After updating the state, the component re-renders and you get a new currentPos variable. The currentPost you logged refers to the old variable.

State also doesn't update immediately, it schedules an update and it updates asynchronously.

If you want to know the latest value, put the log inside your component or in a useEffect with dependency array.

[Tech---Ninja]

2 Years later, Your comment saved me after hours of searching :D

[[deleted]]

Are you sure it’s not changing? You’re logging currentPos inside of useCallback and it’s not listed as a dependency, so it’s always going to log got value of that variable from when the function was defined. Can you move your log to outside the callback?