引入<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-polyfill/7.2.5/polyfill.js"></script>
然后就 es6、es7 特性随便写了，但缺点是，babel-polyfill 包含所有补丁，不管浏览器是否支持，也不管你的项目是否有用到，都全量引了


https://cdnjs.com/  search "babel-polyfill"

https://cdnjs.cloudflare.com/ajax/libs/babel-polyfill/7.10.4/polyfill.js
https://cdnjs.cloudflare.com/ajax/libs/babel-polyfill/7.10.4/polyfill.min.js