export const courter = (state = 0, action) => {
    switch (action.type) {
        case ADD_ONE:
            return state + 1;
        case REMOVE_ONE:
            return state - 1;
        default:
            return state
    }
}

圖上state不是一個物件，此時如果用修飾器因為第一個引數返回必須為物件則

@connect(
    state=>{
        return {num: state.courter}
    },
    {add,remove,addAsync})