报错：Store无有效reducer，传入combineReducers的参数需为合法对象

错误原因 #

你传入configureStore的reducer是一个空对象{}，Redux要求根reducer必须包含至少一个有效的reducer函数，combineReducers会严格校验传入对象的每个值都是合法reducer，空对象不满足这个要求，因此触发报错。

解决方法 #

方法1：添加占位reducer（适合暂时无实际reducer的场景） #

先定义一个最简单的占位reducer，再传入configureStore：

// 占位reducer，返回默认状态
const placeholderReducer = (state = {}, action) => state;

function configureStore_a() {
  const store: any = configureStore({
    reducer: {
      // 加入占位reducer，满足Redux的最少reducer要求
      placeholder: placeholderReducer
    },
  });
 
  store.ascReducers = {};

  return store;
}

方法2：正确实现动态添加reducer（若需后续注入reducers） #

如果是想后续动态添加reducers，不要手动添加ascReducers，用Redux Toolkit自带方式实现：

import { configureStore, combineReducers } from '@reduxjs/toolkit';

// 初始根reducer，包含一个占位
const initialRootReducer = combineReducers({
  placeholder: (state = {}, action) => state
});

function configureStore_a() {
  const store = configureStore({
    reducer: initialRootReducer,
  });

  // 自定义注入reducer的方法
  store.injectReducer = (key: string, reducer: any) => {
    // 合并现有reducer与新reducer，替换根reducer
    const newRootReducer = combineReducers({
      ...store.getState(),
      [key]: reducer
    });
    store.replaceReducer(newRootReducer);
  };

  return store;
}

关键说明 #

• Redux核心是用reducer管理状态，哪怕是占位的空reducer，也必须至少存在一个，否则Store无法初始化。
• 不要直接给store添加自定义属性（比如ascReducers），扩展store功能请遵循Redux官方推荐方式。

内容的提问来源于stack exchange，提问作者Shivam Singh