A warning about using for in loops on the props after Attachments introduction.

[HighFunctioningSociopathSH]

I ran into an issue where Attachments weren't working on my component. Then, after searching for the cause, I found out that "for in" loops don't iterate over the Symbols. Since I don't have much experience with Symbols, I didn't know this fact, I think there might be other developers who might not know this. It would be good to have a warning about it in the docs, since if you try to process the props through a "for in" loop, you will accidentally lose the Attachments.

[brunnerh]

This should be an issue.

[HighFunctioningSociopathSH]

Really? I thought since there's nothing you can do for the "for in" loop behavior, this doesn't qualify as an issue? But if I were to make an issue, I'm not sure what the issue would be. The fix is not that hard, though; you should just spread the original object of props inside your copy before using your "for in" loop. Or you could do a separate "for of" loop on the "Object.getOwnPropertySymbols(props)".

[brunnerh]

You suggested a clarification in the docs, that is an issue as well.

(There is not much that could be done on a technical level other than maybe providing a utility function that copies attachments from one object to another.)

[brunnerh]

This also applies to things like Object.keys and Object.entries, a function for just returning a list of attachments could be useful.

[HighFunctioningSociopathSH]

I made an issue about it. We can discuss it further there. #15929