react 自定义状态管理库

核心实现原理 ：
全局状态容器：维护单一状态源
订阅机制：组件订阅状态变化
状态更新调度：通过 Hooks 触发组件重渲染

基础版实现–核心代码

// 1. 创建全局状态存储
const createStore = (initialState) => {
  let state = initialState
  const listeners = new Set()

  return {
    getState: () => state,
    setState: (newState) => {
      state = typeof newState === 'function' ? newState(state) : newState
      listeners.forEach(listener => listener()) // 通知所有订阅者
    },
    subscribe: (listener) => {
      listeners.add(listener)
      return () => listeners.delete(listener) // 返回取消订阅函数
    }
  }
}

// 2. 创建 React Hook 绑定
const useStore = (store, selector) => {
  const [state, setState] = useState(() => selector(store.getState()))

  useEffect(() => {
    const unsubscribe = store.subscribe(() => {
      const newState = selector(store.getState())
      setState(newState) // 只有当选中的状态变化时才更新
    })
    return unsubscribe
  }, [store, selector])

  return state
}

使用示例

// 创建 store
const counterStore = createStore({ count: 0 })

// 在组件中使用
const Counter = () => {
  const count = useStore(counterStore, state => state.count)
  
  return (
    <div>
      <button onClick={() => counterStore.setState(s => ({ count: s.count - 1 }))}>
        -
      </button>
      <span>{count}</span>
      <button onClick={() => counterStore.setState(s => ({ count: s.count + 1 }))}>
        +
      </button>
    </div>
  )
}