useReducer可配合react-redux方案

接下来我们来看 useReducer
这个属性配合 react-redux 就会非常好用

那么我们编写一段这样代码

import React, { useState } from 'react';

const ContDom = () => {
  const [count, setCount] = useState(0);

  return (
    <div>
      cont值{ count }
      <button onClick = {()=>{ setCount(count + 1) }}>
        增加
      </button>
      <button onClick = {()=>{ setCount(count - 1) }}>
        减少
      </button>
    </div>
  )
}

export default ContDom;

这其实就是实现了一个很基本的数据加减功能
我们点增加 cont的值会一直上涨
在这里插入图片描述
反之点减少值就会一直向下减

但如果我们这个值是react-redux管理的公共数据呢？
由于时间问题我们直接编写代码如下

import React, { useReducer } from 'react';

const initialState = { count: 0 };

const reducer = (state,action) => {
  switch(action.type){
    case "incrment":
      return {count: state.count+1}
    case "decrement":
      return { count: state.count-1 }
    default:
      return state
  }
}

const ContDom = () => {
  const [state, dispatch] = useReducer(reducer, initialState);

  return (
    <div>
      cont值{state && state.count}
      <button onClick = {()=>{ dispatch({type:"incrment"}) }}>
        增加
      </button>
      <button onClick = {()=>{ dispatch({type:"decrement"}) }}>
        减少
      </button>
    </div>
  )
}

export default ContDom;