Zustand State Management Skill

Zustand State Management

Status: Production Ready ✅ Last Updated: 2025-11-21 Latest Version: zustand@5.0.8 Dependencies: React 18+, TypeScript 5+

Quick Start (3 Minutes)

1. Install Zustand

bun add zustand  # preferred
# or: npm install zustand
# or: yarn add zustand

Why Zustand?

Minimal API: Only 1 function to learn (create)
No boilerplate: No providers, reducers, or actions
TypeScript-first: Excellent type inference
Fast: Fine-grained subscriptions prevent unnecessary re-renders
Flexible: Middleware for persistence, devtools, and more

2. Create Your First Store (TypeScript)

import { create } from 'zustand'

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

const useBearStore = create<BearStore>()((set) => ({
  bears: 0,
  increase: (by) => set((state) => ({ bears: state.bears + by })),
  reset: () => set({ bears: 0 }),
}))

CRITICAL: Notice the double parentheses create<T>()() - this is required for TypeScript with middleware.

3. Use Store in Components

import { useBearStore } from './store'

function BearCounter() {
  const bears = useBearStore((state) => state.bears)
  return <h1>{bears} around here...</h1>
}

function Controls() {
  const increase = useBearStore((state) => state.increase)
  return <button onClick={() => increase(1)}>Add bear</button>
}

Why this works:

Components only re-render when their selected state changes
No Context providers needed
Selector function extracts specific state slice

The 3-Pattern Setup Process

Pattern 1: Basic Store (JavaScript)

For simple use cases without TypeScript:

import { create } from 'zustand'

const useStore = create((set) => ({
  count: 0,
  increment: () => set((state) => ({ count: state.count + 1 })),
  decrement: () => set((state) => ({ count: state.count - 1 })),
}))

When to use:

Prototyping
Small apps
No TypeScript in project

Pattern 2: TypeScript Store (Recommended)

For production apps with type safety:

import { create } from 'zustand'

// Define store interface
interface CounterStore {
  count: number
  increment: () => void
  decrement: () => void
}

// Create typed store
const useCounterStore = create<CounterStore>()((set) => ({
  count: 0,
  increment: () => set((state) => ({ count: state.count + 1 })),
  decrement: () => set((state) => ({ count: state.count - 1 })),
}))

Key Points:

Separate interface for state + actions
Use create<T>()() syntax (currying for middleware)
Full IDE autocomplete and type checking

Pattern 3: Persistent Store

For state that survives page reloads:

import { create } from 'zustand'
import { persist, createJSONStorage } from 'zustand/middleware'

interface UserPreferences {
  theme: 'light' | 'dark' | 'system'
  language: string
  setTheme: (theme: UserPreferences['theme']) => void
  setLanguage: (language: string) => void
}

const usePreferencesStore = create<UserPreferences>()(
  persist(
    (set) => ({
      theme: 'system',
      language: 'en',
      setTheme: (theme) => set({ theme }),
      setLanguage: (language) => set({ language }),
    }),
    {
      name: 'user-preferences', // unique name in localStorage
      storage: createJSONStorage(() => localStorage), // optional: defaults to localStorage
    },
  ),
)

Why this matters:

State automatically saved to localStorage
Restored on page reload
Works with sessionStorage too
Handles serialization automatically

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 shallow 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 (5 Issues)

| Issue | Error | Quick Fix | |-------|-------|-----------| | #1 Hydration mismatch | "Text content does not match" | Use _hasHydrated flag + onRehydrateStorage | | #2 TypeScript inference | Types break with middleware | Use create<T>()() double parentheses | | #3 Import error | "createJSONStorage not exported" | Upgrade to zustand@5.0.8+ | | #4 Infinite loop | Browser freezes | Use shallow or separate selectors | | #5 Slices types | StateCreator types fail | Explicit StateCreator<Combined, [], [], Slice> |

Most Critical - TypeScript double parentheses:

// ❌ WRONG: create<T>((set) => ...)
// ✅ CORRECT: create<T>()((set) => ...)

See: references/known-issues.md for complete solutions with code examples.

Middleware Configuration

import { create } from 'zustand'
import { devtools, persist } from 'zustand/middleware'

const useStore = create<MyStore>()(
  devtools(
    persist(
      (set) => ({ /* store definition */ }),
      { name: 'my-storage' },
    ),
    { name: 'MyStore' },
  ),
)

| Middleware | Purpose | Import | |------------|---------|--------| | persist | localStorage/sessionStorage | zustand/middleware | | devtools | Redux DevTools integration | zustand/middleware | | immer | Mutable update syntax | zustand/middleware/immer |

Order matters: devtools(persist(...)) shows persist actions in DevTools.

See: references/middleware-guide.md for complete middleware documentation.

Common Patterns

| Pattern | Use Case | Key Technique | |---------|----------|---------------| | Computed values | Derived data | Compute in selector: state.items.length | | Async actions | API calls | set({ isLoading: true }) + try/catch | | Reset store | Logout, form clear | set(initialState) | | Selector with params | Dynamic access | state.todos.find(t => t.id === id) | | Multiple stores | Separation of concerns | Create separate create() calls |

See: references/common-patterns.md for complete implementations.

Advanced Topics

| Topic | Use Case | Key API | |-------|----------|---------| | Vanilla store | Non-React, testing | createStore() from zustand/vanilla | | Custom middleware | Logging, timestamps | Wrap StateCreator | | Immer | Mutable update syntax | immer() middleware | | Subscriptions | Side effects | store.subscribe() |

See: references/advanced-topics.md for complete implementations.

Bundled Resources

| Type | Files | |------|-------| | 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, typescript-patterns.md, nextjs-hydration.md, migration-guide.md, known-issues.md, common-patterns.md, advanced-topics.md |

When to Load References

| Reference | Load When... | |-----------|--------------| | known-issues.md | Debugging hydration, TypeScript, infinite loop, or slices errors | | common-patterns.md | Implementing computed values, async actions, reset patterns | | advanced-topics.md | Vanilla stores, custom middleware, Immer, subscriptions | | middleware-guide.md | Configuring persist, devtools, or combining middlewares | | typescript-patterns.md | Complex type inference issues, StateCreator problems | | nextjs-hydration.md | Next.js SSR/hydration problems | | migration-guide.md | Migrating from Redux, Context API, or Zustand v4 |

Quick Troubleshooting

| Problem | Solution | |---------|----------| | Store updates don't trigger re-renders | Use selector: useStore(state => state.value) not destructuring | | TypeScript errors with middleware | Use create<T>()() double parentheses | | Hydration error with persist | Implement _hasHydrated flag pattern | | Actions not showing in DevTools | Pass action name: set(newState, undefined, 'actionName') | | Store resets unexpectedly | HMR causes reset in development |

Dependencies

{ "dependencies": { "zustand": "^5.0.8", "react": "^18.0.0+" } }

Compatibility: React 18+, React 19, TypeScript 5+, Next.js 14+, Vite 5+

Official Docs: https://zustand.docs.pmnd.rs/ | GitHub: https://github.com/pmndrs/zustand

Agent Skills: Zustand State Management

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