name: zustand-state-management
description: Best practices for Zustand state management in React and Next.js applications with TypeScript.

Zustand State Management

You are an expert in Zustand state management for React and Next.js applications.

Core Principles

• Use Zustand for lightweight, flexible state management
• Minimize useEffect and setState; prioritize derived state and memoization
• Implement functional, declarative patterns avoiding classes
• Use descriptive variable names with auxiliary verbs like isLoading, hasError

Store Design

Basic Store Structure

import { create } from 'zustand'

interface BearState {
  bears: number
  isLoading: boolean
  hasError: boolean
  increase: () => void
  reset: () => void
}

const useBearStore = create<BearState>((set) => ({
  bears: 0,
  isLoading: false,
  hasError: false,
  increase: () => set((state) => ({ bears: state.bears + 1 })),
  reset: () => set({ bears: 0 }),
}))

Best Practices

• Keep stores focused and modular
• Use selectors to prevent unnecessary re-renders
• Implement middleware for persistence, logging, or devtools
• Separate actions from state when stores grow complex

Integration with React

• Use shallow equality for selecting multiple values
• Combine with TanStack React Query for server state
• Implement proper TypeScript interfaces for type safety
• Use zustand/middleware for persistence and devtools

Performance Optimization

• Select only the state you need in components
• Use shallow comparison for object selections
• Avoid selecting the entire store
• Memoize computed values when necessary

Middleware Usage

Persistence

import { persist } from 'zustand/middleware'

const useStore = create(
  persist(
    (set) => ({
      // state and actions
    }),
    { name: 'store-key' }
  )
)

DevTools

import { devtools } from 'zustand/middleware'

const useStore = create(
  devtools((set) => ({
    // state and actions
  }))
)

Error Handling

• Handle errors at function start using early returns and guard clauses
• Implement error states within stores
• Use try-catch in async actions
• Provide meaningful error messages

Testing

• Test stores independently of components
• Mock Zustand stores in component tests
• Verify state transitions and actions
• Test middleware behavior separately