zustand-state-management

$npx skills add jezweb/claude-skills --skill zustand-state-management
SKILL.md

Zustand State Management

**Last Updated**: 2026-01-21 **Latest Version**: zustand@5.0.10 (released 2026-01-12) **Dependencies**: React 18-19, TypeScript 5+ * * * ```

Zustand State Management

Last Updated: 2026-01-21 Latest Version: zustand@5.0.10 (released 2026-01-12) Dependencies: React 18-19, TypeScript 5+

Quick Start

npm install zustand
TypeScript Store (CRITICAL: use create<T>()() double parentheses):
import { create } from 'zustand'

interface BearStore {
  bears: number
  increase: (by: number) => void
}

const useBearStore = create<BearStore>()((set) => ({
  bears: 0,
  increase: (by) => set((state) => ({ bears: state.bears + by })),
}))
`**Use in Components**:`
const bears = useBearStore((state) => state.bears)  // Only re-renders when bears changes
const increase = useBearStore((state) => state.increase)

Core Patterns

Basic Store (JavaScript):
const useStore = create((set) => ({
  count: 0,
  increment: () => set((state) => ({ count: state.count + 1 })),
}))
`**TypeScript Store** (Recommended):`
interface CounterStore { count: number; increment: () => void }
const useStore = create<CounterStore>()((set) => ({
  count: 0,
  increment: () => set((state) => ({ count: state.count + 1 })),
}))
`**Persistent Store** (survives page reloads):`
import { persist, createJSONStorage } from 'zustand/middleware'

const useStore = create<UserPreferences>()(
  persist(
    (set) => ({ theme: 'system', setTheme: (theme) => set({ theme }) }),
    { name: 'user-preferences', storage: createJSONStorage(() => localStorage) },
  ),
)

Critical Rules

Always Do

✅ Use create<T>()() (double parentheses) in TypeScript for middleware compatibility ✅ Define separate interfaces for state and actions ✅ Use selector functions to extract specific state slices ✅ Use set with updater functions for derived state: set((state) => ({ count: state.count + 1 })) ✅ Use unique names for persist middleware storage keys ✅ Handle Next.js hydration with hasHydrated flag pattern ✅ Use useShallow hook for selecting multiple values ✅ Keep actions pure (no side effects except state updates)

Never Do

❌ Use create<T>(...) (single parentheses) in TypeScript - breaks middleware types ❌ Mutate state directly: set((state) => { state.count++; return state }) - use immutable updates ❌ Create new objects in selectors: useStore((state) => ({ a: state.a })) - causes infinite renders ❌ Use same storage name for multiple stores - causes data collisions ❌ Access localStorage during SSR without hydration check ❌ Use Zustand for server state - use TanStack Query instead ❌ Export store instance directly - always export the hook

Known Issues Prevention

This skill prevents 6 documented issues:

Issue #1: Next.js Hydration Mismatch

Error: "Text content does not match server-rendered HTML" or "Hydration failed"
Source:
Why It Happens: Persist middleware reads from localStorage on client but not on server, causing state mismatch.
Prevention:
import { create } from 'zustand'
import { persist } from 'zustand/middleware'

interface StoreWithHydration {
  count: number
  _hasHydrated: boolean
  setHasHydrated: (hydrated: boolean) => void
  increase: () => void
}

const useStore = create<StoreWithHydration>()(
  persist(
    (set) => ({
      count: 0,
      _hasHydrated: false,
      setHasHydrated: (hydrated) => set({ _hasHydrated: hydrated }),
      increase: () => set((state) => ({ count: state.count + 1 })),
    }),
    {
      name: 'my-store',
      onRehydrateStorage: () => (state) => {
        state?.setHasHydrated(true)
      },
    },
  ),
)

// In component
function MyComponent() {
  const hasHydrated = useStore((state) => state._hasHydrated)

  if (!hasHydrated) {
    return <div>Loading...</div>
  }

  // Now safe to render with persisted state
  return <ActualContent />
}

Issue #2: TypeScript Double Parentheses Missing

Error: Type inference fails, StateCreator types break with middleware
Source: Official Zustand TypeScript Guide
Why It Happens: The currying syntax create<T>()() is required for middleware to work with TypeScript inference.
Prevention:
// ❌ WRONG - Single parentheses
const useStore = create<MyStore>((set) => ({
  // ...
}))

// ✅ CORRECT - Double parentheses
const useStore = create<MyStore>()((set) => ({
  // ...
}))
Rule: Always use create<T>()() in TypeScript, even without middleware (future-proof).

Issue #3: Persist Middleware Import Error

Error: "Attempted import error: 'createJSONStorage' is not exported from 'zustand/middleware'"
Source: GitHub Discussion #2839
Why It Happens: Wrong import path or version mismatch between zustand and build tools.
Prevention:
// ✅ CORRECT imports for v5
import { create } from 'zustand'
import { persist, createJSONStorage } from 'zustand/middleware'

// Verify versions
// zustand@5.0.9 includes createJSONStorage
// zustand@4.x uses different API

// Check your package.json
// "zustand": "^5.0.9"

Issue #4: Infinite Render Loop

Error: Component re-renders infinitely, browser freezes
Uncaught Error: Maximum update depth exceeded. This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate.
Source:
Why It Happens: Creating new object references in selectors causes Zustand to think state changed.
v5 Breaking Change: Zustand v5 made this error MORE explicit compared to v4. In v4, this behavior was "non-ideal" but could go unnoticed. In v5, you'll immediately see the "Maximum update depth exceeded" error.
Prevention:
import { useShallow } from 'zustand/shallow'

// ❌ WRONG - Creates new object every time
const { bears, fishes } = useStore((state) => ({
  bears: state.bears,
  fishes: state.fishes,
}))

// ✅ CORRECT Option 1 - Select primitives separately
const bears = useStore((state) => state.bears)
const fishes = useStore((state) => state.fishes)

// ✅ CORRECT Option 2 - Use useShallow hook for multiple values
const { bears, fishes } = useStore(
  useShallow((state) => ({ bears: state.bears, fishes: state.fishes }))
)

Issue #5: Slices Pattern TypeScript Complexity

Error: StateCreator types fail to infer, complex middleware types break
Source: Official Slices Pattern Guide
Why It Happens: Combining multiple slices requires explicit type annotations for middleware compatibility.
Prevention:
import { create, StateCreator } from 'zustand'

// Define slice types
interface BearSlice {
  bears: number
  addBear: () => void
}

interface FishSlice {
  fishes: number
  addFish: () => void
}

// Create slices with proper types
const createBearSlice: StateCreator<
  BearSlice & FishSlice,  // Combined store type
  [],                      // Middleware mutators (empty if none)
  [],                      // Chained middleware (empty if none)
  BearSlice               // This slice's type
> = (set) => ({
  bears: 0,
  addBear: () => set((state) => ({ bears: state.bears + 1 })),
})

const createFishSlice: StateCreator<
  BearSlice & FishSlice,
  [],
  [],
  FishSlice
> = (set) => ({
  fishes: 0,
  addFish: () => set((state) => ({ fishes: state.fishes + 1 })),
})

// Combine slices
const useStore = create<BearSlice & FishSlice>()((...a) => ({
  ...createBearSlice(...a),
  ...createFishSlice(...a),
}))

Issue #6: Persist Middleware Race Condition (Fixed v5.0.10+)

Error: Inconsistent state during concurrent rehydration attempts
Source:
Why It Happens: In Zustand v5.0.9 and earlier, concurrent calls to rehydrate during persist middleware initialization could cause a race condition where multiple hydration attempts would interfere with each other, leading to inconsistent state.
Prevention: Upgrade to Zustand v5.0.10 or later. No code changes needed - the fix is internal to the persist middleware.
npm install zustand@latest # Ensure v5.0.10+
Note: This was fixed in v5.0.10 (January 2026). If you're using v5.0.9 or earlier and experiencing state inconsistencies with persist middleware, upgrade immediately.

Middleware

Persist (localStorage):
import { persist, createJSONStorage } from 'zustand/middleware'

const useStore = create<MyStore>()(
  persist(
    (set) => ({ data: [], addItem: (item) => set((state) => ({ data: [...state.data, item] })) }),
    {
      name: 'my-storage',
      partialize: (state) => ({ data: state.data }),  // Only persist 'data'
    },
  ),
)
`**Devtools** (Redux DevTools):`
import { devtools } from 'zustand/middleware'

const useStore = create<CounterStore>()(
  devtools(
    (set) => ({ count: 0, increment: () => set((s) => ({ count: s.count + 1 }), undefined, 'increment') }),
    { name: 'CounterStore' },
  ),
)
v4→v5 Migration Note: In Zustand v4, devtools was imported from 'zustand/middleware/devtools'. In v5, use 'zustand/middleware' (as shown above). If you see "Module not found: Can't resolve 'zustand/middleware/devtools'", update your import path.
Combining Middlewares (order matters):
const useStore = create<MyStore>()(devtools(persist((set) => ({ /* ... */ }), { name: 'storage' }), { name: 'MyStore' }))

Common Patterns

Computed/Derived Values (in selector, not stored):
const count = useStore((state) => state.items.length) // Computed on read
Async Actions:
const useAsyncStore = create<AsyncStore>()((set) => ({
  data: null,
  isLoading: false,
  fetchData: async () => {
    set({ isLoading: true })
    const response = await fetch('/api/data')
    set({ data: await response.text(), isLoading: false })
  },
}))
`**Resetting Store**:`
const initialState = { count: 0, name: '' }
const useStore = create<ResettableStore>()((set) => ({
  ...initialState,
  reset: () => set(initialState),
}))
`**Selector with Params**:`
const todo = useStore((state) => state.todos.find((t) => t.id === id))

Bundled Resources

Templates: basic-store.ts, typescript-store.ts, persist-store.ts, slices-pattern.ts, devtools-store.ts, nextjs-store.ts, computed-store.ts, async-actions-store.ts
References: middleware-guide.md (persist/devtools/immer/custom), typescript-patterns.md (type inference issues), nextjs-hydration.md (SSR/hydration), migration-guide.md (from Redux/Context/v4)
Scripts: check-versions.sh (version compatibility)

Advanced Topics

Vanilla Store (Without React):
import { createStore } from 'zustand/vanilla'

const store = createStore<CounterStore>()((set) => ({ count: 0, increment: () => set((s) => ({ count: s.count + 1 })) }))
const unsubscribe = store.subscribe((state) => console.log(state.count))
store.getState().increment()
`**Custom Middleware**:`
const logger: Logger = (f, name) => (set, get, store) => {
  const loggedSet: typeof set = (...a) => { set(...a); console.log(`[${name}]:`, get()) }
  return f(loggedSet, get, store)
}
`**Immer Middleware** (Mutable Updates):`
import { immer } from 'zustand/middleware/immer'

const useStore = create<TodoStore>()(immer((set) => ({
  todos: [],
  addTodo: (text) => set((state) => { state.todos.push({ id: Date.now().toString(), text }) }),
})))
v5.0.3→v5.0.4 Migration Note: If upgrading from v5.0.3 to v5.0.4+ and immer middleware stops working, verify you're using the import path shown above (zustand/middleware/immer). Some users reported issues after the v5.0.4 update that were resolved by confirming the correct import.
Experimental SSR Safe Middleware (v5.0.9+):
Status: Experimental (API may change)
Zustand v5.0.9 introduced experimental unstable_ssrSafe middleware for Next.js usage. This provides an alternative approach to the _hasHydrated pattern (see Issue #1).
import { unstable_ssrSafe } from 'zustand/middleware'

const useStore = create<Store>()(
  unstable_ssrSafe(
    persist(
      (set) => ({ /* state */ }),
      { name: 'my-store' }
    )
  )
)
Recommendation: Continue using the _hasHydrated pattern documented in Issue #1 until this API stabilizes. Monitor Discussion #2740 for updates on when this becomes stable.

Official Documentation