[Feature]: Send events to HTML contexts

[kwvanderlinde]

Describe the Problem

If a frame (or dialog or overlay) needs to reflect the current application state (e.g., current selection, etc), it's a bit painful to accomplish. The onChangeSelection event and similar won't notify the frame itself of the changes. Instead they invoke another macro that is then responsible for reacting to the change, which could involve pushing data to the frame or reloading the frame.

The Solution you'd like

When an onChangeSelection, onChangeImpersonated, onChangeToken, onChangeMap, or onInitiativeChange event is emitted (I think that's all of them), it is also sent as a JavaScript event to any open HTML frame, dialog, or overlay. The event would contain any pertinent details (e.g., selected token ID, current map ID, etc).

It would then be possible to react to such an event in JavaScript, e.g.:

window.addEventListener("onChangeSelection", event => {
	/* Handle it here. */
});

Alternatives that you've considered.

None.

Additional Context

No response

[kwvanderlinde]

I have a framework where I follow this pattern, but have to translate the events myself into JS events. It basically just uses runJSFunction() to inject code like this:

'use strict';
((key, detail) => {
	const event = new CustomEvent(key, { detail: detail });
	window.dispatchEvent(event);
}).call(null, /* event key */, /* event details */);

I don't know if that would be the "right" approach for a built-in equivalent, but it works.