tasssik

import {createStore, combineReducers} from 'redux'
import {cardReducer, anotherReducer} from './reducers'

const reducer = combineReducers({
  cardReducers,
  anotherReducer
})

const initialState = { 
  // some data
  cardReducer: { 
    items: [{id: 1, name: 'book'}, {id: 2, name: 'some song'}]
    // etc
  },
  anotherReducer: { 
    //some another data
  }
}

const store = createStore(reducer, initialState)

так же Вы должны указывать initialState, когда пишете редюсер:

const initialState = {
  items: []
  // some another data
}
export function cardReducer(state = initialState, action) {
  switch(action.type) {
    case types.SOME_ACTION:
    // do some stuff
  default:
    return state // так же возвращается initialState, если еще никаких диспатчев этого рюдесера не происходило.
}

Если Вам надо з сервера получить что-то, то подключаем thunkMiddleware и тогда делаем так:

const FETCH_ALL_ITEMS = 'FETCH_ALL_ITEMS'
const FETCH_ALL_ITEMS_SUCCESS = 'FETCH_ALL_ITEMS_SUCCESS'
const FETCH_ALL_ITEMS_ERROR = 'FETCH_ALL_ITEMS_ERROR'

export function fetchAllItemsFromServer() {
  return (dispatch, getState) => {
    dispatch({type: FETCH_ALL_ITEMS})
    fetch('http://example.com/account/card')
      .then(res => res.toJSON())
      .then(items => dispatch({type: FETCH_ALL_ITEMS_SUCCESS, payload: items}))
      .catch(errors => dispatch({type: FETCH_ALL_ITEMS_ERROR, errors: errors}))
  }
}

export function cardReducer(state = {
  items: [],
  isLoading: false,
  errors: {}
}, action) {
  switch (action.type) {
  case FETCH_ALL_ITEMS:
    return Object.assign({}, state, {
      isLoading: true
    })
  case FETCH_ALL_ITEMS_SUCCESS:
    return Object.assign({}, state, {
      isLoading: false,
      items: action.payload
    })
  case FETCH_ALL_ITEMS_ERROR:
    return Object.assign({}, state, {
      isLoading: false,
      errors: action.errors
    })
  default:
    return state
  }
}

// ну и теперь мы можем задиспатчить наш екшен
store.dispatch(fetchAllItemsFromServer())

// и потом изъять данные из стора
const state = store.getState()