Should Iterator.from and AsyncIterator.from support non-iterable arraylikes

[js-choi]

Array.from supports non-iterable “arraylike” objects: objects that have integer properties and a length property but no Symbol.iterator property. For example, Array.from({ 0: 'a', 1: 'b', 2: 'c', length: 2 }) returns [ 'a', 'b' ].

Array.fromAsync is also going to support non-iterable “arraylike” objects. For example, await Array.fromAsync({ 0: Promise.resolve('a'), 1: Promise.resolve('b'), 2: Promise.resolve('c'), length: 2 }) returns [ 'a', 'b' ].

Array.fromAsync(input) is designed to be equivalent to AsyncIterator.from(input).toArray().
This comes from how Array.from(input) would be equivalent to Iterator.from(input).toArray().

However, they are not actually equivalent, because Iterator.from(input) and AsyncIterator.from(input) do not support non-iterable arraylike inputs. Should they? (I don’t have a strong opinion except that an explicit decision should be made.)

[bakkot]

No, they should not. Array.from (and I guess its async version) should be the one and only way of consuming arraylikes. It's fine for Array.fromAsync and AsyncIterator.from(input).toArray() to differ in this way.