您定义的每个状态片都可以声明可以响应 * 外部 * 操作的reducer函数。这些额外的reducer在切片的extraReducers属性上定义。
Redux的一个关键概念是每个切片缩减器“拥有”它的状态切片，并且许多切片缩减器可以独立地响应相同的动作类型。extraReducers允许createSlice响应除其生成的类型之外的其他操作类型。
示例：
切片X

import { createSlice } from '@reduxjs/toolkit';
import { actionY } from './sliceY';

const sliceX = createSlice({
  name: "X",
  initialState,
  reducers: {
    actionX: (state, action) => {
      // update X state
    },
  },
  extraReducers: builder => {
    builder
      .addCase(actionY, (state, action) => {
        // update X state based on action Y
      });
  },
});

export { actionX } = sliceX.actions;
export default sliceX;

切片Y

import { createSlice } from '@reduxjs/toolkit';
import { actionX } from './sliceX';

const sliceY = createSlice({
  name: "Y",
  initialState,
  reducers: {
    actionY: (state, action) => {
      // update Y state
    },
  },
  extraReducers: builder => {
    builder
      .addCase(actionX, (state, action) => {
        // update Y state based on action X
      });
  },
});

export { actionY } = sliceY.actions;
export default sliceY;