Reactjs '；行动'；未在reducer-React，Redux中定义

我已经设置了一个减速机，但是控制台抱怨没有定义“action”no undef

import { getName } from '../actions';
let defaultState={
 name: "Sam"
}
const mainReducer=(state = defaultState, simpleAction)=>{
if (action.type === "CHANGE_NAME") {
return{
  ...state,
  name: action.name
}

} else {
return{
  ...state
}
}
}

export default mainReducer

---

只需将

simpleAction

更改为

action

执行以下操作：

import { getName } from '../actions';
let defaultState = { name: "Sam" }
const mainReducer = (state = defaultState, action) => {
    if (action.type === "CHANGE_NAME") {
        return { ...state, name: action.name }
    }
    else {
        return { ...state }
    }
}
export default mainReducer

---

它是

simpleAction

它应该是

（state=defaultState，action）