How to use the element-ui/lib/locale.use function in element-ui

import SocialSharing from 'vue-social-sharing'
import Icon from 'vue-awesome/components/Icon'

const _queue = new Queue(10, Infinity)

// Alias i18n function.
const __ = chrome.i18n.getMessage
Vue.prototype.__ = __

// Change docuemnt title manually. Coz title is assign on build stage.
document.title = __('extName')

Vue.config.productionTip = false

const mainLangName = chrome.i18n.getUILanguage().split('-')[0]
locale.use((mainLangName === 'zh') ? zhLocale : enLocale)

// Import element-ui components.
const elements = [
  Slider,
  Loading,
  Button,
  Table,
  TableColumn,
  Tag,
  Tooltip,
  DatePicker,
  Pagination,
  Switch,
  Container,
  Menu,
  MenuItem,

import Vue from 'vue'
import { Form, FormItem, Switch } from 'element-ui'
import 'element-ui/lib/theme-chalk/index.css'
import enLocale from 'element-ui/lib/locale/lang/en'
import zhLocale from 'element-ui/lib/locale/lang/zh-TW'
import locale from 'element-ui/lib/locale'
import root from './root.vue'

Vue.config.productionTip = false

const mainLangName = chrome.i18n.getUILanguage().split('-')[0]
locale.use((mainLangName === 'zh') ? zhLocale : enLocale)

Vue.use(Form, { locale })
Vue.use(FormItem, { locale })
Vue.use(Switch, { locale })

/* eslint-disable no-new */
new Vue({
  el: '#root',
  render: h => h(root)
})

import Vue from 'vue'
import Tippy from 'v-tippy'
import 'typeface-lato/index.css'
import App from './App.vue'
import { Select, Option, OptionGroup, InputNumber, Switch } from 'element-ui'
import lang from 'element-ui/lib/locale/lang/en'
import locale from 'element-ui/lib/locale'

// configure language
locale.use(lang)

Vue.use(Tippy, {
  position: 'top',
  theme: 'light',
  size: 'small',
  animation: 'scale',
  performance: true,
  arrow: true,
  trigger: 'click',
  duration: [200, 200]
})
Vue.use(Select)
Vue.use(Option)
Vue.use(OptionGroup)
Vue.use(InputNumber)
Vue.use(Switch)

import Vue from 'vue';
import Vuex from 'vuex';
import ElementUI from 'element-ui';
import 'element-ui/lib/theme-default/index.css';
import './assets/bootstrap/bootstrap-grid.css';
import './assets/common.css';
import lang from 'element-ui/lib/locale/lang/zh-CN';
import locale from 'element-ui/lib/locale';
import FastClick from 'fastclick';

import router from './router.js';
import App from './App.vue';

Vue.use(Vuex);
Vue.use(ElementUI);
locale.use(lang);

FastClick.attach(document.body);
/* eslint-disable no-new */

const store = new Vuex.Store({
	state: {},
	mutations: {}
});

new Vue({
	router,
	store,
	el: '#app',
	template: '',
	components: {
		App

// The Vue build version to load with the `import` command
// (runtime-only or standalone) has been set in webpack.base.conf with an alias.
import Vue from 'vue';
import App from './App';
import router from './router';

import 'bulma/css/bulma.css'

import ElementUI from 'element-ui'
import 'element-ui/lib/theme-chalk/index.css'
Vue.use(ElementUI)

import lang from 'element-ui/lib/locale/lang/en'
import locale from 'element-ui/lib/locale'

locale.use(lang)

Vue.config.productionTip = false;

/* eslint-disable no-new */
new Vue({
  el: '#app',
  router,
  template: '',
  components: { App },
});

// Backtop,
  // Carousel,
  // CarouselItem,
  // Collapse,
  // CollapseItem,
  // Cascader,
  // ColorPicker,
  // Transfer,
  // Rate,
  // Upload,
  // Slider,
  // Tree,
  // Tooltip,
} from 'element-ui'

locale.use(lang)

Vue.use(Dialog)
Vue.use(Dropdown)
Vue.use(DropdownMenu)
Vue.use(DropdownItem)
Vue.use(Menu)
Vue.use(Submenu)
Vue.use(MenuItem)
Vue.use(MenuItemGroup)
Vue.use(Input)
Vue.use(Button)
Vue.use(ButtonGroup)
Vue.use(Popover)
Vue.use(Form)
Vue.use(FormItem)
Vue.use(Tag)

const localize = lang => {
  switch (lang) {
    case 'zh-CN':
      use(zhLocale)
      break
    default:
      use(enLocale)
  }
}
localize(lang)

Nova.booting(function(Vue, router) {
  locale.use(mapLocales[Nova.config.locale] || mapLocales['en']);
  Vue.use(Select);
  Vue.use(Option);
  Vue.use(Input);
  Vue.use(Autocomplete);
  Vue.use(InputNumber);
  Vue.use(Radio);
  Vue.use(RadioButton);
  Vue.use(RadioGroup);
  Vue.use(Checkbox);
  Vue.use(CheckboxButton);
  Vue.use(CheckboxGroup);
  Vue.use(ColorPicker);
  Vue.use(Tag);
  Vue.use(Switch);
  Vue.use(TabPane);
  Vue.use(Tabs);

import Vue from 'vue'
import en from 'element-ui/lib/locale/lang/en'
import locale from 'element-ui/lib/locale'

locale.use(en);

import {
	Button,
	Menu,
	Submenu,
	MenuItem,
	Tooltip,
	Loading,
	MessageBox,
	Message,
	Notification,
	Table,
	TableColumn,
	RadioGroup,
	Radio,
	Pagination,