fix(combobox, input-time-zone): fix initial item selection delay

[jcfranco]

Related Issue: #10731

Summary

Fixes a combobox regression introduced by #11265 without impacting performance.

Notable changes

• drops debouncing of
  • item update (initial update delay was the main cause of regression)
  • change event emitting
• adds more test coverage for change event emitting
• ignores item-initiated updates until combobox is loaded
• splits up item update logic into the following sections to minimize re-renders:
  • item/data
  • item props
  • selection/filter
  • minor tidy up

[driskull]

👍

[driskull]

nice

[driskull]

shouldn't we still debounce this in some cases? Like the mutation observer case?

[jcfranco]

We could keep an eye out for this. The MO callback kicks in once per batch of mutations, so I don't expect a significant increase in updateItem calls.

[driskull]

Sounds good. We may want to have some internal doc/guidelines on when we should debounce a function and under what circumstances.

[richiecarmichael]

Suggested change

	this.getItems().forEach((item) => {
	item.selected = Array.isArray(value)
	? value.includes(item.value)
	: value
	? value === item.value
	: false;
	});
	for (const item of this.getItems()) {
	item.selected = (Array.isArray(value) && value.includes(item.value)) ||
	(!Array.isArray(value) && value === item.value);
	}

[jcfranco]

I noticed some diffs on the initial render. Looking into this.