Add parent parameter to Component's mounted function

[Wodann]

I'm submitting a feature request for the addition of a parent: &Element - that implements the IParentNode trait - to the fn mounted(&self) of a Component:

fn mounted(&self, parent: &Element)

Instead of having to look through the entire document tree to find the current element, we'd be able to use the parent node to execute any desired JS, resulting in a significant speed up.

[davidkna]

Something like html! { <div onmount=|element| Msg::Mounted(element) /> } for regular elements would also be nice.

[jstarry]

@hgzimmerman @Wodann would refs solve this issue? We could potentially enforce those at compile time

[hgzimmerman]

I don't have a full comprehension of how refs work in this context, but if you think an alternative approach instead of my quick and dirty solution can more accurately constrain possible misuses of the API, or ultimately offer something simpler to use, please favor that instead.

[Wodann]

A Reference (doc) should be sufficient for downcasting to an Element - or any type of HTML element for that matter. However, Element already implements IParentNode and thus makes ergonomics easier.

For me, the question is whether we could ever have a parent that is not an Element? No right? So then we might as well use Element. That can then be converted to specific element types using try_into, which still has a check built in.

[jstarry]

@Wodann @hgzimmerman this is what I had in mind: #665

[Wodann]

@jstarry That seems like an efficient solution 👍

[jstarry]

Closing in favour of refs approach