「zustand」更够快速构建你的项目状态管理方案

zustand

Zustand 是由一个名为 pmndrs 的团队开发和维护的状态管理库。
pmndrs 是一个由多位开发者组成的团队，专注于构建开源工具和库来推动 Web 开发的进步。

zustand优势

简单易用: Zustand 的 API 设计简单直观，学习曲线较低。与其他一些状态管理库相比，Zustand 提供了更少的概念和 API，减少了开发者的认知负担。
基于钩子: Zustand 使用 React 的钩子机制作为状态管理的基础。它通过创建自定义 Hook 来提供对状态的访问和更新。这种方式与函数式组件和钩子的编程模型紧密配合，使得状态管理变得非常自然和无缝。
可拓展性: Zustand 提供了中间件 (middleware) 的概念，允许你通过插件的方式扩展其功能。中间件可以用于处理日志记录、持久化存储、异步操作等需求，使得状态管理更加灵活和可扩展。
性能优化: Zustand 在设计时非常注重性能。它采用了高效的状态更新机制，避免了不必要的渲染。同时，Zustand 还支持分片状态和惰性初始化，以提高大型应用程序的性能。
无副作用: Zustand 鼓励无副作用的状态更新方式。它倡导使用 immer 库来处理不可变性，使得状态更新更具可预测性，也更易于调试和维护。

图为：新一代状态管理方案，目前已经有 34k Star.

快速上手 —— 3 步实现基础状态管理

安装

npm install zustand // 
yarn add zustand


// 计数器 Demo 快速上手
import React from "react";
import { create } from "zustand";

const useStore = create()((set) => ({
  count: 0,
  setCount: (num: number) => set({ count: num }),
  inc: () => set((state) => ({ count: state.count + 1 })),
}));

export default function Demo() {
  // 在这里引入所需状态
  const { count, setCount, inc } = useStore();

  return (
    <div>
      {count}
      <input
        onChange={(event) => {
          setCount(Number(event.target.value));
        }}
      ></input>
      <button onClick={inc}>增加</button>
    </div>
  );
}

快速上手 —— 分解步骤

导入 create 函数

import { create } from 'zustand';

创建 Store

const useStore = create()((set) => ({
  count: 0,
  setCount: (num: number) => set({ count: num }),
  inc: () => set((state) => ({ count: state.count + 1 })),
}));

使用State

export default function Demo() {
  // 在这里引入所需状态
  const { count, setCount, inc } = useStore();

  return (
    <div>
      {count}
      <input
        onChange={(event) => {
          setCount(Number(event.target.value));
        }}
      ></input>
      <button onClick={inc}>增加</button>
    </div>
  );
}

zustand 与 redux 进行对比

react-redux 版本

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()
  // ...
}

toolkit版本

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 版本

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 , increment , decrement} = useCountStore();
  // ...
}

对比下来，zustand简直不要太简单

reset state 重置状态

单仓库重置

直接传入reset函数, 使用时调用reset函数

import { create } from 'zustand'

// define types for state values and actions separately
type State = {
  salmon: number
  tuna: number
}

type Actions = {
  addSalmon: (qty: number) => void
  addTuna: (qty: number) => void
  reset: () => void
}

// define the initial state
const initialState: State = {
  salmon: 0,
  tuna: 0,
}

// create store
const useSlice = create<State & Actions>()((set, get) => ({
  ...initialState,

  addSalmon: (qty: number) => {
    set({ salmon: get().salmon + qty })
  },

  addTuna: (qty: number) => {
    set({ tuna: get().tuna + qty })
  },

  reset: () => {
    set(initialState)
  },
}))

多仓库重置

import { create as _create, StateCreator } from 'zustand'

const resetters: (() => void)[] = []

export const create = (<T extends unknown>(f: StateCreator<T> | undefined) => {
  if (f === undefined) return create
  const store = _create(f)
  const initialState = store.getState()
  resetters.push(() => {
    store.setState(initialState, true)
  })
  return store
}) as typeof _create

export const resetAllStores = () => {
  for (const resetter of resetters) {
    resetter()
  }
}

async operation 异步操作

zustand 不会单独区分异步操作，可直接进行异步即可

const useStore = create((set) => ({
  obj: {},
  fetch: async (req) => {
    const response = await fetch(req)
    set({ obj: await response.json() })
  },
}))

middleware中间件

持久化存储

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

export const useBearStore = create(
  persist(
    (set, get) => ({
      bears: 0,
      addABear: () => set({ bears: get().bears + 1 }),
    }),
    {
      name: 'food-storage', // name of the item in the storage (must be unique)
      storage: createJSONStorage(() => sessionStorage), // (optional) by default, 'localStorage' is used
    }
  )
)

监控日志

// state 每次发生变化都将输出日志
const log = (config) => (set, get, api) =>
  config(
    (...args) => {
      console.log('  applying', args)
      set(...args)
      console.log('  new state', get())
    },
    get,
    api
  )

immer不可变数据实现

import { create } from 'zustand'
import { immer } from 'zustand/middleware/immer'

type State = {
  count: number
}

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

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

Devtools middle 开发者工具调试state

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

const useFishStore = create(
  devtools(persist(
    (set, get) => ({
      fishes: 0,
      addAFish: () => set({ fishes: get().fishes + 1 }),
    }),
  ))
)

如果你仍然想写redux

import { redux } from 'zustand/middleware'

const types = { increase: 'INCREASE', decrease: 'DECREASE' }

const reducer = (state, { type, by = 1 }) => {
  switch (type) {
    case types.increase:
      return { grumpiness: state.grumpiness + by }
    case types.decrease:
      return { grumpiness: state.grumpiness - by }
  }
}

const initialState = {
  grumpiness: 0,
  dispatch: (args) => set((state) => reducer(state, args)),
}

const useReduxStore = create(redux(reducer, initialState))

笔者推荐的 zustand 代码格式

import React from "react";
import { create } from "zustand";

// define types for state values and actions separately
type States = {
  salmon: number;
  tuna: number;
};

type Actions = {
  addSalmon: (qty: number) => void;
  addTuna: (qty: number) => void;
  reset: () => void;
};

// define the initial state
const initialState: States = {
  salmon: 0,
  tuna: 0
};

// create store
const useSlice = create<States & Actions>()((set, get) => ({
  ...initialState,
  addSalmon: (qty: number) => {
    set({ salmon: get().salmon + qty });
  },
  addTuna: (qty: number) => {
    set({ tuna: get().tuna + qty });
  },
  reset: () => {
    set(initialState);
  }
}));


export default function App() {
    // const {salmon,addSalmon,tuna,addTuna,reset} = useSlice();

    // value
    const { salmon, tuna } = useSlice();
    // aciton
    const { addSalmon, addTuna, reset } = useSlice();

    return (
        <div className="App">
            {salmon}{" "}
            <button type="button" onClick={() => addSalmon(1)}>
                Add Salmon
            </button>
            <hr />
            {tuna}{" "}
            <button type="button" onClick={() => addTuna(1)}>
                Add Tuna
            </button>
            <hr />
            <button type="button" onClick={() => reset()}>
                Reset
            </button>
            
        </div>
    );
}