Clean way to wait for first true returned by Promise

Question

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([Promis         


        

Answer 1

You can implement that combining Promise.race and 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);
}

Test for above code:

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]);