按需引入组件时，message、notification等会自动弹出

vue

import { Button, Notification, Row, Col, Collapse, CollapseItem } from 'element-ui'
Vue.component(Button.name, Button)
Vue.component(Notification.name, Notification)
Vue.component(Row.name, Row)
Vue.component(Col.name, Col)
Vue.component(CollapseItem.name, CollapseItem)
Vue.component(Collapse.name, Collapse)

Vue.prototype.$notify = Notification

//使用Vue.use(Notification)也会直接弹出提示框