如何以组方式调用一个异步函数? [英] How can I call one asynchronous function in a group way?

问题描述

很抱歉，我可能无法清楚地描述此问题.我会尝试:

I am sorry that I may not be able to describe this issue clearly. I will try:

现在我有一个异步函数，该函数接收数据并执行某些操作，例如

Now I have one asynchronous function which takes data and do something, e.g.

function myFunction(num: number):Promise<void> {
   return new Promise((resolve) => {
     console.log(num);
     return;
   });
} 

我想在一个组中打印5个数字(顺序无关紧要).重要的是，我想在上一组结束后打印下5个数字. 例如:

I want to print 5 numbers in a group (the order doesn't matter). What matters is that I want to print the next 5 numbers after the previous group finishes. For example:

1, 2, 5, 4, 3, 6, 9, 8, 7, 10 ... is valid
7, 10, 1, 2, 3, 4, 5, 6, 8, 9 ... is not valid

如果必须使用此功能，该如何实现?我必须确保已解决此函数的前五个调用，然后加快对后五个函数的调用.我知道这看起来很奇怪，我正在尝试将当前问题简化为数字问题.

How can I make this happen if I have to use this function? I have to maker sure the first five calls of this function have been resolved and then spin up calls of the next five functions. I know this seems weird, I'm trying to abstract my current problem into this number problem.

谢谢您的任何评论或想法.

Thank you for any comments or idea.

推荐答案

您可以通过将数组分成多个块并使用Array#map和Promise#all处理这些块来实现此目的.然后，您可以使用Array#reduce:

You can accomplish this by breaking an array into chunks and processing the chunks using Array#map and Promise#all. You can then string the chunk processing together using Array#reduce:

runChunkSeries([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 5, someAsyncFn);

// our placeholder asynchronous function
function someAsyncFn(value) {
  return new Promise((resolve) => {
    setTimeout(resolve, Math.random() * 5000);
  }).then(() => console.log(value));
}

function runChunkSeries(arr, chunkSize, fn) {
  return runSeries(chunk(arr, chunkSize), (chunk) => Promise.all(chunk.map(fn)));
}

// Run fn on each element of arr asynchronously but in series
function runSeries(arr, fn) {
  return arr.reduce((promise, value) => {
    return promise.then(() => fn(value));
  }, Promise.resolve());
}

// Creates an array of elements split into groups the length of chunkSize
function chunk(arr, chunkSize) {
  const chunks = [];
  const {length} = arr;
  const chunkCount = Math.ceil(length / chunkSize);

  for(let i = 0; i < chunkCount; i++) {
    chunks.push(arr.slice(i * chunkSize, (i + 1) * chunkSize));
  }

  return chunks;
}

这是一个有效的 codepen .

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