vue-cli 按需引入element ui

element ui是饿了么出品的ui框架，按需引入可以提高程序的性能

首先安装所需要的插件babel

npm install babel-plugin-component --save

然后，按照官方文档给出的 修改.babelrc是不可以覆盖的，会出错，所以方法就是整合，例如下方的代码

{
  "presets": [
    ["env", {
      "modules": false,
      "targets": {
        "browsers": ["> 1%", "last 2 versions", "not ie <= 8"]
      }
    }],
    ["es2015", { "modules": false }],
    "stage-2"
  ],
  "plugins": ["transform-vue-jsx", "transform-runtime",["component",{"libraryName": "element-ui","styleLibraryName": "theme-chalk"}]]
}

如果报了如下的错误

未安装es2015

安装相应的插件

npm install babel-preset-es2015 --save

在main.js中写入以下内容，将你不使用的组件删除即可

import Vue from 'vue'
import {
  Pagination,
  Dialog,
  Autocomplete,
  Dropdown,
  DropdownMenu,
  DropdownItem,
  Menu,
  Submenu,
  MenuItem,
  MenuItemGroup,
  Input,
  InputNumber,
  Radio,
  RadioGroup,
  RadioButton,
  Checkbox,
  CheckboxButton,
  CheckboxGroup,
  Switch,
  Select,
  Option,
  OptionGroup,
  Button,
  ButtonGroup,
  Table,
  TableColumn,
  DatePicker,
  TimeSelect,
  TimePicker,
  Popover,
  Tooltip,
  Breadcrumb,
  BreadcrumbItem,
  Form,
  FormItem,
  Tabs,
  TabPane,
  Tag,
  Tree,
  Alert,
  Slider,
  Icon,
  Row,
  Col,
  Upload,
  Progress,
  Badge,
  Card,
  Rate,
  Steps,
  Step,
  Carousel,
  CarouselItem,
  Collapse,
  CollapseItem,
  Cascader,
  ColorPicker,
  Transfer,
  Container,
  Header,
  Aside,
  Main,
  Footer,
  Loading,
  MessageBox,
  Message,
  Notification
} from 'element-ui'

Vue.use(Pagination)
Vue.use(Dialog)
Vue.use(Autocomplete)
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(InputNumber)
Vue.use(Radio)
Vue.use(RadioGroup)
Vue.use(RadioButton)
Vue.use(Checkbox)
Vue.use(CheckboxButton)
Vue.use(CheckboxGroup)
Vue.use(Switch)
Vue.use(Select)
Vue.use(Option)
Vue.use(OptionGroup)
Vue.use(Button)
Vue.use(ButtonGroup)
Vue.use(Table)
Vue.use(TableColumn)
Vue.use(DatePicker)
Vue.use(TimeSelect)
Vue.use(TimePicker)
Vue.use(Popover)
Vue.use(Tooltip)
Vue.use(Breadcrumb)
Vue.use(BreadcrumbItem)
Vue.use(Form)
Vue.use(FormItem)
Vue.use(Tabs)
Vue.use(TabPane)
Vue.use(Tag)
Vue.use(Tree)
Vue.use(Alert)
Vue.use(Slider)
Vue.use(Icon)
Vue.use(Row)
Vue.use(Col)
Vue.use(Upload)
Vue.use(Progress)
Vue.use(Badge)
Vue.use(Card)
Vue.use(Rate)
Vue.use(Steps)
Vue.use(Step)
Vue.use(Carousel)
Vue.use(CarouselItem)
Vue.use(Collapse)
Vue.use(CollapseItem)
Vue.use(Cascader)
Vue.use(ColorPicker)
Vue.use(Container)
Vue.use(Header)
Vue.use(Aside)
Vue.use(Main)
Vue.use(Footer)

Vue.use(Loading.directive)

Vue.prototype.$loading = Loading.service
Vue.prototype.$msgbox = MessageBox
Vue.prototype.$alert = MessageBox.alert
Vue.prototype.$confirm = MessageBox.confirm
Vue.prototype.$prompt = MessageBox.prompt
Vue.prototype.$notify = Notification
Vue.prototype.$message = Message