干净的方法来等待Promise返回的第一个true [英] Clean way to wait for first true returned by Promise

问题描述

我目前正在做一些我要在数组中实现三个承诺的事情.目前看起来像这样

I'm currently working on something where I fire out three promises in an array. At the moment it looks something like this

var a = await Promise.all([Promise1(), Promise2(), Promise3()]);

现在，所有这些承诺都将返回true或false.但是目前，我正在等待所有这些操作完成，只要其中一个返回true，我就可以继续.

Now all of those promises will either return true or false. But at the moment I'm waiting for all of them to be finished and I could go on as soon as one of them returns true.

我想到了实现此目标的方法，但似乎都有些丑陋.您将如何解决此任务?

I thought of ways to accomplish that but all seem kind of ugly. How would you solve this task?

推荐答案

您可以结合使用 Promise.race 和 Promise.all :

function firstTrue(promises) {
    const newPromises = promises.map(p => new Promise(
        (resolve, reject) => p.then(v => v && resolve(true), reject)
    ));
    newPromises.push(Promise.all(promises).then(() => false));
    return Promise.race(newPromises);
}

测试以上代码:

function firstTrue(promises) {
  const newPromises = promises.map(p => new Promise(
    (resolve, reject) => p.then(v => v && resolve(true), reject)
  ));
  newPromises.push(Promise.all(promises).then(() => false));
  return Promise.race(newPromises);
}

var test = values => firstTrue(
  values.map((v) => new Promise((resolve) => {
    setTimeout(() => resolve(v), Math.round(Math.random() * 1000));
  }))
).then((ret) => console.log(values, ret));

test([true, true, true]);
test([false, false, false]);
test([true, false, false]);
test([false, true, false]);
test([false, false, true]);

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