vuex/examples/classic/todomvc/store/index.js

import { createStore } from 'vuex'
import { mutations, STORAGE_KEY } from './mutations'
import actions from './actions'
import plugins from './plugins'

export default createStore({
  state: {
    todos: JSON.parse(window.localStorage.getItem(STORAGE_KEY) || '[]')
  },
  actions,
  mutations,
  plugins
})