串行执行返回promise的函数 [英] Serial execution of functions returning promises

问题描述

凭借ES2016，我们现在有了承诺，这很棒。不幸的是，该功能非常简约，并且没有像async包中可用的系列或瀑布那样。
如果有一个为promises提供此功能的软件包，或者人们通常如何处理这些用例？

With ES2016 we now have promises and that's great. Unfortunately the functionality is very minimalistic and there is nothing like the series or waterfall as available in the async package. If there a package providing this functionality for promises or how do people typically deal with those use cases?

推荐答案

To串行执行一系列函数返回你可以使用的promise Array.prototype.reduce ：

To serially execute an array of functions returning promises you can use Array.prototype.reduce:

let final = functions.reduce((prev, f) => prev.then(f), Promise.resolve());

初始参数 Promise.resolve（）是否为promises链设定种子，否则（如果传递的数组只包含一个函数）， .reduce 回调永远不会被调用。

The "initial" argument Promise.resolve() is there to seed the chain of promises, since otherwise (if passed an array containing only a single function) the .reduce callback never gets called.

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