在vue-cli2中引入element-ui以及报错解决

1. 安装element-ui
   cnpm install element-ui --save
2. 在main.js文件当中进行配置

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

3. npm run serve启动项目
   遇到报错：

R babel-runtime/helpers/extends in ./node_modules/_async-validator@1.8.5@async-validator/es/index.js
R babel-runtime/helpers/typeof in ./node_modules/_async-validaton1.8.5@iasync-validator/es/index.js，./node_moduls/_async-validator@1.8.5@async-validator/es/rule/type.js and 1 other
o install them，you can run: npm install --save babel-runtime/helpers/extends babel-runtime/helpers/typeof

解决办法：重新安装
cnpm uninstall element-ui --save
cnpm install element-ui --save

ps：这里在网上找了很多种方法都没用，没想到最后重新安装就可以了
贴一个链接，说不定有帮助：
https://segmentfault.com/q/1010000020918347