npm install --save babel-polyfill
在main.js中添加：
import es6Promise from "babel-polyfill";
es6Promise .polyfill();
在webpack.base.conf.js中修改
module.exports = { entry: ["babel-polyfill", "./app/js"] };
但是还是发现报错：
polyfill-eventsource added missing EventSource to window
这时候再下载event-source-polyfill模块
npm install event-source-polyfill --save-dev
并将webpack.base.conf.js修改为：
module.exports = { entry: ["event-source-polyfill", "babel-polyfill", "./app/js"] };
https://babeljs.io/docs/usage/polyfill/
https://github.com/vuejs-templates/webpack/issues/474
