promise

async/await

https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Guide/Using_promises

之前这个其实没学明白, 看了这个文档, 决定看看是否改造一下我的代码.

估计把这几篇看了就明白了:

  1. https://medium.com/@bluepnume/learn-about-promises-before-you-start-using-async-await-eb148164a9c8
  2. https://javascript.info/async
  3. https://codeburst.io/node-express-async-code-and-error-handling-121b1f0e44ba