It is shorter to write than a for of loop, and importantly, all images will be loaded in parallel rather than sequentially, which can be significantly faster.
images = Promise.all(uris.map(loadImage))On the other hand, the language designers are not random framework authors. They know what they're doing. There must be some reason why `Promise.all` exists. I just don't know what it is.
To re-iterate, I understand the difference between serial and parallel tasks. But I have also found that it's possible to do parallel tasks with `await` in a loop. So I'm still missing something.
As others have mentioned; if you aren’t using Promise.all, you are likely missing a good deal of opportunities for easier and more performant async code.
The "inner workings" could be a for loop, with the exception of rejected promises. The only opportunity for quicker resolution is when one of the promises reject, at which time Promise.all() immediately rejects.
I think the allegations of "easier" are significantly overblown too.
// A -- Async and parallel
const results = await Promise.all(data.map((i) => delay(i)));
// B -- Functionally equivalent to the above
const promises = data.map((i) => delay(i));
const result = [];
for (let a of promises) {
const r = await a;
result.push(r);
}
// C -- Problematic and naive approach: much slower
const result = [];
for (let i of data) {
const r = await delay(i);
result.push(r);
}