Reactjs 为什么MapStateTops中的状态未定义？

reducers/counter.js

export type counterStateType = {
  +ctr: number,
  +counter: boolean
};

type actionType = {
  +type: string,
  +value: any
};    

export default function counter(state: counterStateType = { ctr: 0, counter: true}, action: actionType) {
  console.log("Reducer called with");
  console.log(state);//has valid value ie { ctr: 0, counter: true}  
  switch (action.type) {
    case TOGGLE:
      state.counter = !state.counter;
      return state;
    case UPDATE:
      state.ctr = action.value;
      return state;
    default:
      return state;
  }
}

counterPage.js

function mapStateToProps(state) {
  console.log("mapStateToProps called with");
  console.log(state.counter);

  return {
    ctr: state.counter.ctr,//<= undefined
    counter: state.counter.counter
  };
}

function mapDispatchToProps(dispatch) {
  return bindActionCreators(CounterActions, dispatch);
}

export default connect(mapStateToProps, mapDispatchToProps)(Counter);

函数MapStateTops（状态）{
log（“调用的mapStateToProps”）；
console.log（state.counter）；
返回{
ctr:state.counter.ctr，//问题出在reducer中，我忘记了redux状态的不可变性。修改

  switch (action.type) {
    case TOGGLE:
      state.counter = !state.counter;
      return state;
    case UPDATE:
      state.ctr = action.value;
      return state;
    default:
      return state;
  }

到

解决了它。
检查什么是状态。计数器它是从打印状态本身开始的，但为了方便起见，现在更新了问题。您的计数器最初为true，现在在MapStateTops中为false。您可以显示更新计数器对象的代码和更新计数器对象的reducer。解决了问题，问题在reducer中，这里我省略了我对减速机的状态更新进行了修改，但问题就在那里。
  switch (action.type) {
    case TOGGLE:
      return {ctr: state.ctr, counter: !state.counter};
    case UPDATE:
      return {ctr: action.value, counter: state.counter};
    default:
      return state;
  }