使用Bluebird Promises做N次 [英] Do something N times using Bluebird Promises

问题描述

我正在尝试每个人都感到非常兴奋的Promises.应该减少它们的代码复杂性，这是我尚未观察到的功能.

I am trying the Promises everyone is so excited about. They're are supposed to reduce code complexity which is a feature I've yet to observe.

就我而言，我有一个返回Promise的函数.该函数通过ADB在Android设备上调用向上或向下键事件.我这样称呼它:

In my case, I have a function that returns Promise. The function invokes key up or down event on Android device over ADB. I call it like this:

press(B_KEY, 3000, client, device)
  .then(function(result) {console.log("Key press done.");});

我想按顺序执行几次此动作(调用press).我可以手动执行此操作:

I would like to perform this action (call the press) function) several times in sequence. I can do this manually:

press(B_KEY, 3000, client, device)
  .then(function(result) {return press(B_KEY, 3000, client, device);})
  .then(function(result) {return press(B_KEY, 3000, client, device);})
  .then(function(result) {return press(B_KEY, 3000, client, device);})
  // ad nauseam

我想要类似for的循环.我试图想到伪代码来向您展示，但是我的任何想法都很难看.

I would like to have something like for loop. I tried to think of pseudocode to show you, but any ideas I have are really ugly.

如何使用Promises中的所有功能进行for循环?

How to make for loop with all it's features in Promises?

推荐答案

要实现您的目标，您可以使用mapSeries()在空数组上迭代n次:

To achieve your goal you could use mapSeries() to iterate n times over an empty array:

    return Promise.mapSeries(new Array(4), function() {
        return press(B_KEY, 3000, client, device);
    });

有关mapSeries()的更多信息，请参见参考

For more info about mapSeries() see the reference

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