context-state

context-state

React hooks 状态管理方案

🔧 安装

pnpm add context-state

✨ 介绍

React Context 和 useContext 存在一些性能问题，当 context 上下文改变时，所有使用到 context 的组件都会更新渲染。 使用 context-state，开发者不必考虑 context 穿透问题 👏

🎈 Example

import React from 'react'
import { createContainer, useMemoizedFn } from 'context-state'

function useCounter() {
  const [count, setCount] = React.useState(0)
  const increment = useMemoizedFn(() => setCount((c) => c + 1))

  return {
    count,
    increment,
  }
}

const CounterContainer = createContainer(useCounter)

function CounterDisplay() {
  const { count, increment } = CounterContainer.usePicker(['count', 'increment'])

  return (
    <div>
      {count}
      <button type='button' onClick={increment}>
        ADD
      </button>
    </div>
  )
}

function App() {
  return (
    <CounterContainer.Provider>
      <CounterDisplay />
    </CounterContainer.Provider>
  )
}

render(<App />, document.getElementById('root'))

🐱‍💻 API

createContainer(useHook)

import { createContainer, useMemoizedFn } from 'context-state'

function useCustomHook() {
  const [value, setInput] = useState()
  const onChange = useMemoizedFn((e) => setValue(e.currentTarget.value))
  return {
    value,
    onChange,
  }
}

const Container = createContainer(useCustomHook)
// Container === { Provider, usePicker }

<Container.Provider>

const Container = createContainer(useCustomHook)
function ParentComponent({ children }) {
  return <Container.Provider>{children}</Container.Provider>
}

<Container.Provider value>

function useCustomHook(value = '') {
  const [value, setValue] = useState(value)
  // ...
}

const Container = createContainer(useCustomHook)

function ParentComponent({ children }) {
  return (
    <Container.Provider value='value'>
      {children}
    </Container.Provider>
  )
}

Container.useSelector()

监听当前容器中选择后的值，若值发生改变，则触发 rerender

function ChildComponent() {
  const value = Container.useSelector((state) => state.value)
  return <span>{value}</span>
}

Container.usePicker()

useSelector 的语法糖

function ChildComponent() {
  const { value } = Container.usePicker(['value'])
  return <span>{value}</span>
}

useMemoizedFn

持久化 function 的 Hook。（来自 ahooks 中 useMemoizedFn）

你可能会需要用 useCallback 记住一个回调，但由于内部函数必须经常重新创建，记忆效果不佳，导致子组件重复 render。对于复杂的子组件，重新渲染会对性能造成影响。通过 useMemoizedFn，可以保证函数地址永远不会变化。

💡 灵感来源

unstated-next | use-context-selector