export, import 的用法详解
笔记借鉴：
es6阮一峰-import、export学习：
https://blog.csdn.net/ChuY123/article/details/117227119?utm_medium=distribute.pc_relevant.none-task-blog-baidujs_title-0&spm=1001.2101.3001.4242
ES6 （阮一峰日志）学习笔记：
https://blog.csdn.net/bingo_ShenWei/article/details/81669824?utm_source=blogxgwz6&utm_medium=distribute.pc_relevant.none-task-blog-baidujs_title-1&spm=1001.2101.3001.4242
export学习笔记(Es6阮一峰)：
https://blog.csdn.net/annehc/article/details/100982501
export default用法：
https://www.cnblogs.com/qq254980080/p/10321564.html