Node.js：调用递归函数的后处理结果

Question

我需要处理延迟调用外部服务器的对象数组，将所有结果收集到数组中并对它们进行后处理。示例在这里：(async () => {  const serverOperation = () => new Promise(resolve => setTimeout(() => resolve(), 2000));  const myOtherFunction = results => console.log('results', results);  const objectsArray = [{}, {}, {}];  const results = [];  const myFunc = async arr => {    const el = arr.shift();    if (!el) {      // finish of calling recursive function      return;    }    // some big server operation    const result = await serverOperation();    results.push(result);    // need to wait for some time    setTimeout(async () => {      console.log(Date.now());      await myFunc(arr);    }, 3000);  };  await myFunc(objectsArray);  await myOtherFunction(results);  // <= postprocessing results})();问题是：myOtherFunction在我得到所有结果之前调用了该函数。我的问题是：如何对所有处理结果进行后处理？

Answer 1

您可以使用超时 Promise来延迟函数的执行，而不是setTimeout.

您的代码的问题是，即使您将async函数传递给setTimeout它也不会停止当前函数的执行。setTimeout只会将任务移动到微任务队列并执行传递给它的函数。但它不会导致您的父函数停止，因为传递给的函数setTimeout不会立即调用 - 它稍后会在不同的时间、不同的地方调用。

(async () => {

  const serverOperation = () => new Promise(resolve => setTimeout(() => resolve('server op'), 2000));

  const myOtherFunction = results => console.log('results', results);

  const objectsArray = [{}, {}, {}];

  const results = [];

  

  // used for delaying operations

  const timeoutPromise = () => new Promise(resolve => setTimeout(() => resolve(), 3000));

  const myFunc = async arr => {

    const el = arr.shift();

    if (!el) {

      // finish of calling recursive function

      return;

    }

    // some big server operation

    const result = await serverOperation();

    results.push(result);

    // need to wait for some time

    await timeoutPromise();

    

    console.log(Date.now());

    

    await myFunc(arr);

  };

  await myFunc(objectsArray);

  await myOtherFunction(results);  // <= postprocessing results

})();