http://www.ruanyifeng.com/blog/2012/12/asynchronous%EF%BC%BFjavascript.html Javascript异步编程的4种方法
http://www.html5online.com.cn/articles/2015051301.html fetch()方法介绍
https://segmentfault.com/a/1190000003810652 fetch
原文：http://www.cnblogs.com/duyanli/p/6295654.html