Support for Array Prototype Iteration Methods?

[machineghost]

Any chance this proposal could get a 2.0 version that adds support for asynchronous mapping, filtering, reducing, etc.?

[Jamesernator]

What you're asking for is already at stage 2: https://github.com/tc39/proposal-iterator-helpers

[machineghost]

Awesome news, thanks! It's a little unclear from that proposal that you'll be able to do:

const asyncSum = await urls.reduce(async (sum, url) => {
    const response = await fetch(url);
    const { number } = await response.json();
   return sum + number;
}, 0);

but if it does that will be a truly great language improvement :-)

[Jamesernator]

Awesome news, thanks! It's a little unclear from that proposal that you'll be able to do:

Not if urls is an Array, but you can just wrap it using AsyncIterator.from:

const asyncSum = await AsyncIterator.from(urls).reduce(async (sum, url) => {
    const response = await fetch(url);
    const { number } = await response.json();
   return sum + number;
}, 0);

[devsnek]

If it's an array you can do urls.values().reduce(...)

[Jamesernator]

If it's an array you can do urls.values().reduce(...)

That won't work for the given example, as then the sum argument would be a promise as urls.values() is a sync iterator.

[machineghost]

Seems like it would be a lot simpler to instead have:

const asyncSum = await urls.asyncReduce(async (sum, url) => {
    const response = await fetch(url);
    const { number } = await response.json();
   return sum + number;
}, 0);

... but beggars can't be choosers :-D

[karlhorky]

Added an PR with an example similar to the one from @Jamesernator to the readme of the proposal: tc39/proposal-iterator-helpers#124

[karlhorky]

Not if urls is an Array, but you can just wrap it using AsyncIterator.from

The example inspired by @Jamesernator has been accepted for the readme of https://github.com/tc39/proposal-iterator-helpers 🎉

tc39/proposal-iterator-helpers@dd76e00#diff-b335630551682c19a781afebcf4d07bf978fb1f8ac04c6bf87428ed5106870f5R66-R74