Zustand

Zustand is a small, fast, and scalable bearbones state management solution. Zustand has a comfy API based on hooks. It isn’t boilerplatey or opinionated, but has enough convention to be explicit and flux-like.

ノート

Don’t disregard it because it’s cute, it has claws! Lots of time was spent to deal with common pitfalls, like the dreaded zombie child problem, React concurrency, and context loss between mixed renderers. It may be the one state manager in the React space that gets all of these right.

Usage

First Create a Store

Your store is a hook! You can put anything in it: primitives, objects, functions. The set function merges state.

import { create } from 'zustand'

const useStore = create((set) => ({
  bears: 0,
  increasePopulation: () => set((state) => ({ bears: state.bears + 1 })),
  removeAllBears: () => set({ bears: 0 }),
  updateBears: (newBears) => set({ bears: newBears }),
}))

Then Bind your Components, and that’s it!

You can use the hook anywhere, without the need of providers. Select your state and the consuming component will re-render when that state changes.

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

function Controls() {
  const increasePopulation = useStore((state) => state.increasePopulation)
  return <button onClick={increasePopulation}>one up</button>
}

Comparison

ヒント

How Zustand stacks up against similar libraries

Zustand is one of many state management libraries for React. On this page we will discuss Zustand in comparison to some of these libraries, including Redux, Valtio, Jotai, and Recoil.

Each library has its own strengths and weaknesses, and we will compare key differences and similarities between each.

Zustand vs Redux

State Model

Conceptually, Zustand and Redux are quite similar, both are based on an immutable state model. However, Redux requires your app to be wrapped in context providers; Zustand does not.

Zustand

import { create } from 'zustand'

type State = {
  count: number
}

type Actions = {
  increment: (qty: number) => void
  decrement: (qty: number) => void
}

const useCountStore = create<State & Actions>((set) => ({
  count: 0,
  increment: (qty: number) => set((state) => ({ count: state.count + qty })),
  decrement: (qty: number) => set((state) => ({ count: state.count - qty })),
}))

import { create } from 'zustand'

type State = {
  count: number
}

type Actions = {
  increment: (qty: number) => void
  decrement: (qty: number) => void
}

type Action = {
  type: keyof Actions
  qty: number
}

const countReducer = (state: State, action: Action) => {
  switch (action.type) {
    case 'increment':
      return { count: state.count + action.qty }
    case 'decrement':
      return { count: state.count - action.qty }
    default:
      return state
  }
}

const useCountStore = create<State & Actions>((set) => ({
  count: 0,
  dispatch: (action: Action) => set((state) => countReducer(state, action)),
}))

Redux

import { createStore } from 'redux'
import { useSelector, useDispatch } from 'react-redux'

type State = {
  count: number
}

type Action = {
  type: 'increment' | 'decrement'
  qty: number
}

const countReducer = (state: State, action: Action) => {
  switch (action.type) {
    case 'increment':
      return { count: state.count + action.qty }
    case 'decrement':
      return { count: state.count - action.qty }
    default:
      return state
  }
}

const countStore = createStore(countReducer)

import { createSlice, configureStore } from '@reduxjs/toolkit'

const countSlice = createSlice({
  name: 'count',
  initialState: { value: 0 },
  reducers: {
    incremented: (state, qty: number) => {
      // Redux Toolkit does not mutate the state, it uses the Immer library
      // behind scenes, allowing us to have something called "draft state".
      state.value += qty
    },
    decremented: (state, qty: number) => {
      state.value -= qty
    },
  },
})

const countStore = configureStore({ reducer: countSlice.reducer })

Render Optimization

When it comes to render optimizations within your app, there are no major differences in approach between Zustand and Redux. In both libraries it is recommended that you manually apply render optimizations by using selectors.

Zustand

import { create } from 'zustand'

type State = {
  count: number
}

type Actions = {
  increment: (qty: number) => void
  decrement: (qty: number) => void
}

const useCountStore = create<State & Actions>((set) => ({
  count: 0,
  increment: (qty: number) => set((state) => ({ count: state.count + qty })),
  decrement: (qty: number) => set((state) => ({ count: state.count - qty })),
}))

const Component = () => {
  const count = useCountStore((state) => state.count)
  const increment = useCountStore((state) => state.increment)
  const decrement = useCountStore((state) => state.decrement)
  // ...
}

Redux

import { createStore } from 'redux'
import { useSelector, useDispatch } from 'react-redux'

type State = {
  count: number
}

type Action = {
  type: 'increment' | 'decrement'
  qty: number
}

const countReducer = (state: State, action: Action) => {
  switch (action.type) {
    case 'increment':
      return { count: state.count + action.qty }
    case 'decrement':
      return { count: state.count - action.qty }
    default:
      return state
  }
}

const countStore = createStore(countReducer)

const Component = () => {
  const count = useSelector((state) => state.count)
  const dispatch = useDispatch()
  // ...
}

import { useSelector } from 'react-redux'
import type { TypedUseSelectorHook } from 'react-redux'
import { createSlice, configureStore } from '@reduxjs/toolkit'

const countSlice = createSlice({
  name: 'count',
  initialState: { value: 0 },
  reducers: {
    incremented: (state, qty: number) => {
      // Redux Toolkit does not mutate the state, it uses the Immer library
      // behind scenes, allowing us to have something called "draft state".
      state.value += qty
    },
    decremented: (state, qty: number) => {
      state.value -= qty
    },
  },
})

const countStore = configureStore({ reducer: countSlice.reducer })

const useAppSelector: TypedUseSelectorHook<typeof countStore.getState> =
  useSelector

const useAppDispatch: () => typeof countStore.dispatch = useDispatch

const Component = () => {
  const count = useAppSelector((state) => state.count.value)
  const dispatch = useAppDispatch()
  // ...
}

Zustand vs Valtio

State Model

Zustand and Valtio approach state management in a fundamentally different way. Zustand is based on the immutable state model, while Valtio is based on the mutable state model.

Zustand

import { create } from 'zustand'

type State = {
  obj: { count: number }
}

const store = create<State>(() => ({ obj: { count: 0 } }))

store.setState((prev) => ({ obj: { count: prev.obj.count + 1 } }))

Valtio

import { proxy } from 'valtio'

const state = proxy({ obj: { count: 0 } })

state.obj.count += 1

Render Optimization

The other difference between Zustand and Valtio is Valtio makes render optimizations through property access. However, with Zustand, it is recommended that you manually apply render optimizations by using selectors.

Zustand

import { create } from 'zustand'

type State = {
  count: number
}

const useCountStore = create<State>(() => ({
  count: 0,
}))

const Component = () => {
  const count = useCountStore((state) => state.count)
  // ...
}

Valtio

import { proxy, useSnapshot } from 'valtio'

const state = proxy({
  count: 0,
})

const Component = () => {
  const { count } = useSnapshot(state)
  // ...
}

Zustand vs Jotai

State Model

There are two major differences between Zustand and Jotai. Firstly, Zustand is a single store, while Jotai consists of primitive atoms that can be composed together. Secondly, a Zustand store is an external store, making it more suitable when access outside of React is required.

Zustand

import { create } from 'zustand'

type State = {
  count: number
}

type Actions = {
  updateCount: (
    countCallback: (count: State['count']) => State['count'],
  ) => void
}

const useCountStore = create<State & Actions>((set) => ({
  count: 0,
  updateCount: (countCallback) =>
    set((state) => ({ count: countCallback(state.count) })),
}))

Jotai

import { atom } from 'jotai'

const countAtom = atom<number>(0)

Render Optimization

Jotai achieves render optimizations through atom dependency. However, with Zustand it is recommended that you manually apply render optimizations by using selectors.

Zustand

import { create } from 'zustand'

type State = {
  count: number
}

type Actions = {
  updateCount: (
    countCallback: (count: State['count']) => State['count'],
  ) => void
}

const useCountStore = create<State & Actions>((set) => ({
  count: 0,
  updateCount: (countCallback) =>
    set((state) => ({ count: countCallback(state.count) })),
}))

const Component = () => {
  const count = useCountStore((state) => state.count)
  const updateCount = useCountStore((state) => state.updateCount)
  // ...
}

Jotai

import { atom, useAtom } from 'jotai'

const countAtom = atom<number>(0)

const Component = () => {
  const [count, updateCount] = useAtom(countAtom)
  // ...
}

Zustand vs Recoil

State Model

The difference between Zustand and Recoil is similar to that between Zustand and Jotai. Recoil depends on atom string keys instead of atom object referential identities. Additionally, Recoil needs to wrap your app in a context provider.

Zustand

import { create } from 'zustand'

type State = {
  count: number
}

type Actions = {
  setCount: (countCallback: (count: State['count']) => State['count']) => void
}

const useCountStore = create<State & Actions>((set) => ({
  count: 0,
  setCount: (countCallback) =>
    set((state) => ({ count: countCallback(state.count) })),
}))

Recoil

import { atom } from 'recoil'

const count = atom({
  key: 'count',
  default: 0,
})

Render Optimization

Similar to previous optimization comparisons, Recoil makes render optimizations through atom dependency. Whereas with Zustand, it is recommended that you manually apply render optimizations by using selectors.

Zustand

import { create } from 'zustand'

type State = {
  count: number
}

type Actions = {
  setCount: (countCallback: (count: State['count']) => State['count']) => void
}

const useCountStore = create<State & Actions>((set) => ({
  count: 0,
  setCount: (countCallback) =>
    set((state) => ({ count: countCallback(state.count) })),
}))

const Component = () => {
  const count = useCountStore((state) => state.count)
  const setCount = useCountStore((state) => state.setCount)
  // ...
}

Recoil

import { atom, useRecoilState } from 'recoil'

const countAtom = atom({
  key: 'count',
  default: 0,
})

const Component = () => {
  const [count, setCount] = useRecoilState(countAtom)
  // ...
}

Useful Resources

• Zustand Docs https://docs.pmnd.rs/zustand/getting-started/introduction