web.dom-collections.iterator polyfill added on Object iteration

[igneel64]

Hey peeps 😄

Going through the extracted core-js polyfills for some of our code, I noticed that a large portion of web.dom-collections.iterator polyfills are being added, without our project depending so much on DOMCollection iterations.

Looking a bit more closely I noticed that for...of loops are triggering this polyfill.
Babel repl reproduction

Is this the expected behaviour ? If yes, the documentation of this polyfill seemed not so clear to me.

Thanks!

[zloirock]

Yes, this is expected behavior. With statical analysis, we can't determine the type of obj, so we add default iterators on iteration: array iterator, string iterator, iterators of DOM collections. The rest iterators, for example, map iterator, added on an instance of related type creation. With your targets (Safari > 12), array and string iterator are not required, so added only iterators of DOM collections.

If the documentation of this is not clear for you - it's not a correct place for it and issues about it, it should be documented on Babel side - you could create an issue about it here https://github.com/babel/website.