Better interop with Javascript libraries (React, Svelte, etc.)

[superchris]

@markevans

Out of interest, in LiveElements I see for listening to events it’s using the phx-custom-event-hook - what does this send as parameters to handle_event? Is it the CustomEvent event.detail? In the Komodo library I was umming and ahing about what to send back over the wire by default because I didn’t want accidental big payloads being sent back (e.g. the whole event object) so I ended up making the user be explicit about what gets sent as the payload, but not sure if that’s best. I guess also sometimes you might want event.clientX or something though that’s more for clicks so maybe event.detail is fine…

It had been a minute since I touched this code, so I had to go look to refresh my memory For the payload of the event I send up to the phoenix channel, I take the custom element detail property and also merge in the element data set (any attributes that start with data-). This seems to give enough flexibility to do what I need to do in the cases I’ve encountered so far.