tanstack-query

Use the useQuery hook with a unique queryKey array and a queryFn that returns a promise. TanStack Query automatically caches the result, deduplicates requests, and refetches stale data in the background based on your staleTime configuration.

In useMutation's onMutate callback, cancel outgoing queries with cancelQueries, snapshot the current cache with getQueryData, then update it with setQueryData. Return the snapshot as context and restore it in onError to roll back failed mutations.

staleTime controls how long data is considered fresh before refetching, while gcTime controls how long unused cached data stays in memory before garbage collection. Setting staleTime higher than gcTime can cause data to be collected while still marked fresh.

Yes, useInfiniteQuery handles cursor-based infinite scrolling with getNextPageParam and fetchNextPage. For traditional pagination, use useQuery with the page in the queryKey and placeholderData set to the previous data to avoid loading flickers.

Queries retry failed requests three times by default, which slows tests. Set retry to false and gcTime to Infinity in the test QueryClient, and always wrap tested components with a fresh QueryClientProvider to avoid shared cache state.