[rdom] comment nodes cause exception

This may be ill-advised, but I was hoping that I could add comments to the DOM from rdom. Long story short: special content and exposition for those who care to inspect.

From hiccup: https://github.com/thi-ng/umbrella/blob/2065c927cfe52fe72534fcc0ee74260c760d9966/packages/hiccup/src/serialize.ts#L118-L119

However, trying to use this form from rdom results in an exception in the browser:

I can’t tell exactly what path the __COMMENT__ tag would follow through rdom’s $el a priori, but it seems like a properly oriented document.createComment() in that function might work. If you think this approach is worth pursuing, I’d be more than glad to submit a PR.

[postspectacular]

@usernolan - so sorry again, really didn’t mean to beat you to your first PR to this project!!! 😩 I’m sure there’ll another chance for you!

[postspectacular]

Hi @usernolan 👋 - that’s a good question and TBH the first time I ever thought about that. Taking a look at the $el it seems the problem will be that the created element (or now comment) will have to be returned, however the JS native Comment type unfortunately is not a normal Element:

https://github.com/microsoft/TypeScript/blob/cee6366c4871e42ea05a38d5011128fe932b6591/lib/lib.dom.d.ts#L3652-L3654

https://github.com/microsoft/TypeScript/blob/cee6366c4871e42ea05a38d5011128fe932b6591/lib/lib.dom.d.ts#L4858-L4967

So in short, putting in the extra check & branch to create a comment node is the easy part, but then we would also have to change the return type of $el and that’s where things start to get complicated. At first glance I think it would even cause a breaking change for user component code, but first I will have to take a closer look at all the call sites and some of the secondary effects in user code in more detail… 👍

If you want to work on a PR, then by all means - happy to guide you! 😃