multiple-slices.js

// todos.js 
import { createSlice } from '@reduxjs/toolkit'

const todosSlice = createSlice({
  name: 'todos',
  initialState: [], 
  reducers: {
    addTodo(state, action) {
      const { id, text } = action.payload
      state.push({ id, text, completed: false })
    },
    toggleTodo(state, action) {
      const todo = state.find(todo => todo.id === action.payload)
      if (todo) {
        todo.completed = !todo.completed
      }
    }
  }
})

export const { addTodo, toggleTodo } = todosSlice.actions
export default todosSlice.reducer
 
// visibilityFilter.js
const filtersSlice = createSlice({
  name: 'visibilityFilters',
  initialState: 'SHOW_ALL',
  reducers: {
    setVisibilityFilter(state, action) {
      return action.payload
    }
  }
})

export const { setVisibilityFilter } = filtersSlice.actions
export default filtersSlice.reducer

// rootReducer.js
import { combineReducers } from '@reduxjs/toolkit'

import todosReducer from './todos'
import visibilityFilterReducer from './visibilityFilter'

export default combineReducers({
  todos: todosReducer,
  visibilityFilter: visibilityFilterReducer
})

// store.js
import { configureStore } from '@reduxjs/toolkit'

import rootReducer from './rootReducer.js'

const store = configureStore({ reducer: rootReducer })