TanStack Query (React Query) v5

Last Updated: 2026-01-20 Versions: @tanstack/react-query@5.90.19, @tanstack/react-query-devtools@5.91.2 Requires: React 18.0+ (useSyncExternalStore), TypeScript 4.7+ (recommended)

---

v5 New Features

useMutationState - Cross-Component Mutation Tracking

Access mutation state from anywhere without prop drilling:

import { useMutationState } from '@tanstack/react-query'

function GlobalLoadingIndicator() {
  // Get all pending mutations
  const pendingMutations = useMutationState({
    filters: { status: 'pending' },
    select: (mutation) => mutation.state.variables,
  })

  if (pendingMutations.length === 0) return null
  return <div>Saving {pendingMutations.length} items...</div>
}

// Filter by mutation key
const todoMutations = useMutationState({
  filters: { mutationKey: ['addTodo'] },
})

Simplified Optimistic Updates

New pattern using variables - no cache manipulation, no rollback needed:

function TodoList() {
  const { data: todos } = useQuery({ queryKey: ['todos'], queryFn: fetchTodos })

  const addTodo = useMutation({
    mutationKey: ['addTodo'],
    mutationFn: (newTodo) => api.addTodo(newTodo),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['todos'] })
    },
  })

  // Show optimistic UI using variables from pending mutations
  const pendingTodos = useMutationState({
    filters: { mutationKey: ['addTodo'], status: 'pending' },
    select: (mutation) => mutation.state.variables,
  })

  return (
    <ul>
      {todos?.map(todo => <li key={todo.id}>{todo.title}</li>)}
      {/* Show pending items with visual indicator */}
      {pendingTodos.map((todo, i) => (
        <li key={`pending-${i}`} style={{ opacity: 0.5 }}>{todo.title}</li>
      ))}
    </ul>
  )
}

throwOnError - Error Boundaries

Renamed from useErrorBoundary (breaking change):

import { QueryErrorResetBoundary } from '@tanstack/react-query'
import { ErrorBoundary } from 'react-error-boundary'

function App() {
  return (
    <QueryErrorResetBoundary>
      {({ reset }) => (
        <ErrorBoundary onReset={reset} fallbackRender={({ resetErrorBoundary }) => (
          <div>
            Error! <button onClick={resetErrorBoundary}>Retry</button>
          </div>
        )}>
          <Todos />
        </ErrorBoundary>
      )}
    </QueryErrorResetBoundary>
  )
}

function Todos() {
  const { data } = useQuery({
    queryKey: ['todos'],
    queryFn: fetchTodos,
    throwOnError: true, // ✅ v5 (was useErrorBoundary in v4)
  })
  return <div>{data.map(...)}</div>
}

Network Mode (Offline/PWA Support)

Control behavior when offline:

const queryClient = new QueryClient({
  defaultOptions: {
    queries: {
      networkMode: 'offlineFirst', // Use cache when offline
    },
  },
})

// Per-query override
useQuery({
  queryKey: ['todos'],
  queryFn: fetchTodos,
  networkMode: 'always', // Always try, even offline (for local APIs)
})

Detecting paused state:

const { isPending, fetchStatus } = useQuery(...)
// isPending + fetchStatus === 'paused' = offline, waiting for network

useQueries with Combine

Combine results from parallel queries:

const results = useQueries({
  queries: userIds.map(id => ({
    queryKey: ['user', id],
    queryFn: () => fetchUser(id),
  })),
  combine: (results) => ({
    data: results.map(r => r.data),
    pending: results.some(r => r.isPending),
    error: results.find(r => r.error)?.error,
  }),
})

// Access combined result
if (results.pending) return <Loading />
console.log(results.data) // [user1, user2, user3]

infiniteQueryOptions Helper

Type-safe factory for infinite queries (parallel to queryOptions):

import { infiniteQueryOptions, useInfiniteQuery, prefetchInfiniteQuery } from '@tanstack/react-query'

const todosInfiniteOptions = infiniteQueryOptions({
  queryKey: ['todos', 'infinite'],
  queryFn: ({ pageParam }) => fetchTodosPage(pageParam),
  initialPageParam: 0,
  getNextPageParam: (lastPage) => lastPage.nextCursor,
})

// Reuse across hooks
useInfiniteQuery(todosInfiniteOptions)
useSuspenseInfiniteQuery(todosInfiniteOptions)
prefetchInfiniteQuery(queryClient, todosInfiniteOptions)

maxPages - Memory Optimization

Limit pages stored in cache for infinite queries:

useInfiniteQuery({
  queryKey: ['posts'],
  queryFn: ({ pageParam }) => fetchPosts(pageParam),
  initialPageParam: 0,
  getNextPageParam: (lastPage) => lastPage.nextCursor,
  getPreviousPageParam: (firstPage) => firstPage.prevCursor, // Required with maxPages
  maxPages: 3, // Only keep 3 pages in memory
})

Note: maxPages requires bi-directional pagination (getNextPageParam AND getPreviousPageParam).

---

Quick Set

...