Setup with Next.js

Next.js is a popular server-side rendering framework for React that presents some unique challenges for using Zustand properly. Keep in mind that Zustand store is a global variable (AKA module state) making it optional to use a Context. These challenges include:

• Per-request store: A Next.js server can handle multiple requests simultaneously. This means that the store should be created per request and should not be shared across requests.
• SSR friendly: Next.js applications are rendered twice, first on the server and again on the client. Having different outputs on both the client and the server will result in "hydration errors." The store will have to be initialized on the server and then re-initialized on the client with the same data in order to avoid that. Please read more about that in our SSR and Hydration guide.
• SPA routing friendly: Next.js supports a hybrid model for client side routing, which means that in order to reset a store, we need to intialize it at the component level using a Context.
• Server caching friendly: Recent versions of Next.js (specifically applications using the App Router architecture) support aggressive server caching. Due to our store being a module state, it is completely compatible with this caching.

We have these general recommendations for the appropriate use of Zustand:

• No global stores - Because the store should not be shared across requests, it should not be defined as a global variable. Instead, the store should be created per request.
• React Server Components should not read from or write to the store - RSCs cannot use hooks or context. They aren't meant to be stateful. Having an RSC read from or write values to a global store violates the architecture of Next.js.

Let's write our store factory function that will create a new store for each request.

// tsconfig.json
{
  "compilerOptions": {
    "lib": ["dom", "dom.iterable", "esnext"],
    "allowJs": true,
    "skipLibCheck": true,
    "strict": true,
    "noEmit": true,
    "esModuleInterop": true,
    "module": "esnext",
    "moduleResolution": "bundler",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "jsx": "preserve",
    "incremental": true,
    "plugins": [
      {
        "name": "next"
      }
    ],
    "paths": {
      "@/*": ["./src/*"]
    }
  },
  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
  "exclude": ["node_modules"]
}

Note: do not forget to remove all comments from your tsconfig.json file.

// src/stores/counter-store.ts
import { createStore } from 'zustand/vanilla'

export type CounterState = {
  count: number
}

export type CounterActions = {
  decrementCount: () => void
  incrementCount: () => void
}

export type CounterStore = CounterState & CounterActions

export const defaultInitState: CounterState = {
  count: 0,
}

export const createCounterStore = (
  initState: CounterState = defaultInitState,
) => {
  return createStore<CounterStore>()((set) => ({
    ...initState,
    decrementCount: () => set((state) => ({ count: state.count - 1 })),
    incrementCount: () => set((state) => ({ count: state.count + 1 })),
  }))
}

Let's use the createCounterStore in our component and share it using a context provider.

// src/providers/counter-store-provider.tsx
'use client'

import { type ReactNode, createContext, useRef, useContext } from 'react'
import { type StoreApi, useStore } from 'zustand'

import { type CounterStore, createCounterStore } from '@/stores/counter-store'

export const CounterStoreContext = createContext<StoreApi<CounterStore> | null>(
  null,
)

export interface CounterStoreProviderProps {
  children: ReactNode
}

export const CounterStoreProvider = ({
  children,
}: CounterStoreProviderProps) => {
  const storeRef = useRef<StoreApi<CounterStore>>()
  if (!storeRef.current) {
    storeRef.current = createCounterStore()
  }

  return (
    <CounterStoreContext.Provider value={storeRef.current}>
      {children}
    </CounterStoreContext.Provider>
  )
}

export const useCounterStore = <T,>(
  selector: (store: CounterStore) => T,
): T => {
  const counterStoreContext = useContext(CounterStoreContext)

  if (!counterStoreContext) {
    throw new Error(`useCounterStore must be use within CounterStoreProvider`)
  }

  return useStore(counterStoreContext, selector)
}

Note: In this example, we ensure that this component is re-render-safe by checking the value of the reference, so that the store is only created once. This component will only be rendered once per request on the server, but might be re-rendered multiple times on the client if there are stateful client components located above this component in the tree, or if this component also contains other mutable state that causes a re-render.

// src/stores/counter-store.ts
import { createStore } from 'zustand/vanilla'

export type CounterState = {
  count: number
}

export type CounterActions = {
  decrementCount: () => void
  incrementCount: () => void
}

export type CounterStore = CounterState & CounterActions

export const initCounterStore = (): CounterState => {
  return { count: new Date().getFullYear() }
}

export const defaultInitState: CounterState = {
  count: 0,
}

export const createCounterStore = (
  initState: CounterState = defaultInitState,
) => {
  return createStore<CounterStore>()((set) => ({
    ...initState,
    decrementCount: () => set((state) => ({ count: state.count - 1 })),
    incrementCount: () => set((state) => ({ count: state.count + 1 })),
  }))
}

// src/providers/counter-store-provider.tsx
'use client'

import { type ReactNode, createContext, useRef, useContext } from 'react'
import { type StoreApi, useStore } from 'zustand'

import {
  type CounterStore,
  createCounterStore,
  initCounterStore,
} from '@/stores/counter-store'

export const CounterStoreContext = createContext<StoreApi<CounterStore> | null>(
  null,
)

export interface CounterStoreProviderProps {
  children: ReactNode
}

export const CounterStoreProvider = ({
  children,
}: CounterStoreProviderProps) => {
  const storeRef = useRef<StoreApi<CounterStore>>()
  if (!storeRef.current) {
    storeRef.current = createCounterStore(initCounterStore())
  }

  return (
    <CounterStoreContext.Provider value={storeRef.current}>
      {children}
    </CounterStoreContext.Provider>
  )
}

export const useCounterStore = <T,>(
  selector: (store: CounterStore) => T,
): T => {
  const counterStoreContext = useContext(CounterStoreContext)

  if (!counterStoreContext) {
    throw new Error(`useCounterStore must be use within CounterStoreProvider`)
  }

  return useStore(counterStoreContext, selector)
}

There are two architectures for a Next.js application: the Pages Router and the App Router. The usage of Zustand on both architectures should be the same with slight differences related to each architecture.

// src/components/pages/home-page.tsx
import { useCounterStore } from '@/providers/counter-store-provider.ts'

export const HomePage = () => {
  const { count, incrementCount, decrementCount } = useCounterStore(
    (state) => state,
  )

  return (
    <div>
      Count: {count}
      <hr />
      <button type="button" onClick={() => void incrementCount()}>
        Increment Count
      </button>
      <button type="button" onClick={() => void decrementCount()}>
        Decrement Count
      </button>
    </div>
  )
}

// src/_app.tsx
import type { AppProps } from 'next/app'

import { CounterStoreProvider } from '@/providers/counter-store-provider.tsx'

export default function App({ Component, pageProps }: AppProps) {
  return (
    <CounterStoreProvider>
      <Component {...pageProps} />
    </CounterStoreProvider>
  )
}

// src/pages/index.tsx
import { HomePage } from '@/components/pages/home-page.tsx'

export default function Home() {
  return <HomePage />
}

Note: creating a store per route would require creating and sharing the store at page (route) component level. Try not to use this if you do not need to create a store per route.

// src/pages/index.tsx
import { CounterStoreProvider } from '@/providers/counter-store-provider.tsx'
import { HomePage } from '@/components/pages/home-page.tsx'

export default function Home() {
  return (
    <CounterStoreProvider>
      <HomePage />
    </CounterStoreProvider>
  )
}

// src/components/pages/home-page.tsx
'use client'

import { useCounterStore } from '@/providers/counter-store-provider'

export const HomePage = () => {
  const { count, incrementCount, decrementCount } = useCounterStore(
    (state) => state,
  )

  return (
    <div>
      Count: {count}
      <hr />
      <button type="button" onClick={() => void incrementCount()}>
        Increment Count
      </button>
      <button type="button" onClick={() => void decrementCount()}>
        Decrement Count
      </button>
    </div>
  )
}

// src/app/layout.tsx
import type { Metadata } from 'next'
import { Inter } from 'next/font/google'
import './globals.css'

import { CounterStoreProvider } from '@/providers/counter-store-provider'

const inter = Inter({ subsets: ['latin'] })

export const metadata: Metadata = {
  title: 'Create Next App',
  description: 'Generated by create next app',
}

export default function RootLayout({
  children,
}: Readonly<{
  children: React.ReactNode
}>) {
  return (
    <html lang="en">
      <body className={inter.className}>
        <CounterStoreProvider>{children}</CounterStoreProvider>
      </body>
    </html>
  )
}

// src/app/page.tsx
import { HomePage } from '@/components/pages/home-page'

export default function Home() {
  return <HomePage />
}

Note: creating a store per route would require creating and sharing the store at page (route) component level. Try not to use this if you do not need to create a store per route.

// src/app/page.tsx
import { CounterStoreProvider } from '@/providers/counter-store-provider'
import { HomePage } from '@/components/pages/home-page'

export default function Home() {
  return (
    <CounterStoreProvider>
      <HomePage />
    </CounterStoreProvider>
  )
}