Should collection.getKeys() generally be avoided for iteration/enumeration?

[lixiaoyan]

After #9545, there are still several places in this repo that call .getKeys() directly. I'm not sure whether all of them will eventually run into the same kind of problem — but at least some of them will.

Context

I'm implementing a breadcrumbs component for our internal component library, and I looked at S2's implementation as a reference. That's when I noticed these lines:

react-spectrum/packages/@react-spectrum/s2/src/Breadcrumbs.tsx

Lines 455 to 461 in 8ae29fa

	let children = useMemo(() => {
	let result: Node<any>[] = [];
	for (let key of collection.getKeys()) {
	result.push(collection.getItem(key)!);
	}
	return result;
	}, [collection]);

Admittedly, the odds of a breadcrumbs component's items being reordered are pretty low. I also haven't had time to audit whether the remaining getKeys() calls are affected as well. Still, I wanted to raise the question.

[snowystinger]

It's probably best to not rely on the order of getKeys, instead using an iterator with getKeyAfter. Are you seeing a problem though? if not, we haven't either, so it's probably pretty low on the priorities at the moment.

[lixiaoyan]

Yeah, I know. I haven't actually run into any issues yet — I just wanted to record this somewhere. If something concrete comes up, I'll file an issue.