component.Base: afterSetIsLoading() => findIndex() => findLastIndex

[tobiu]

I know this one is close to overengineering :)

IF a component has a really big amount of direct child items (e.g. root UL tag which 100s of LI child nodes), we can find the target node a tiny bit faster in case we are iterating backwards over the array, since we are adding the load mask as the last child item.