如何从localStorage设置初始initialState的reducer

Question

我有一个购物车网站和用户购物车存储在localStorage。

现在，当我的页面刷新时，我想用我的localStorage初始化我的商店，但是我收到了这个错误：

localStorage is not defined

cart.reducer.js：

import { cartConstants } from '../constants';
import { cartHelper } from '../helpers'

const initialState = []

function cart(state = initialState, action) {
  if(state.length == 0){
    state = cartHelper.getCart(); // error line
  }

  switch (action.type) {
    case cartConstants.CART:
      return action.cart

    default:
      return state
  }
}


export default cart