正常导入import {NavMenu} from 'element-ui';会报错
因此要
import {Menu,Submenu, MenuItem,MenuItemGroup} from 'element-ui';
Vue.use(Menu)
Vue.use(Submenu)
Vue.use(MenuItem)
Vue.use(MenuItemGroup)
参考 https://blog.csdn.net/qq_41556706/article/details/81167170
面包屑的按需引入
import {Breadcrumb,BreadcrumbItem} from 'element-ui'