API Reference

keepPreviousData

function keepPreviousData<T>(previousData: T | undefined): T | undefined;

function keepPreviousData<T>(previousData: T | undefined): T | undefined;

Defined in: packages/query-core/src/utils.ts:582

Intended to be passed as a query's placeholderData option, for example placeholderData: keepPreviousData. Instead of resetting the query's data to undefined while a new query key is fetching, it keeps displaying the previously fetched data until the new data arrives.

Type Parameters

T

Parameters

previousData

T | undefined

The data of the previous query key, passed by the observer.

Returns

T | undefined

The previous data, unchanged.

Example

new QueryObserver(queryClient, {
  queryKey: ['posts', page],
  queryFn: () => fetchPosts(page),
  placeholderData: keepPreviousData,
})

new QueryObserver(queryClient, {
  queryKey: ['posts', page],
  queryFn: () => fetchPosts(page),
  placeholderData: keepPreviousData,
})

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