[proposal] implement virtualization

[DRiFTy17]

Proposal

This feature would enable our dropdowns to allow for an infinite lists of elements, as well as be generic enough to use around any scrollable set of elements to only render what is actually in view within the scroll container. This is a performance improvement across the board, but also introduces the capability to utilize new UX patterns that may not have been as feasible beforehand.

At time of writing, we have a specialized/focused implementation for use with our dropdowns only here.

Eventually it would be our goal to provide a generic/reusable virtual scroller Web Component for consumers to utilize in their application for any scrollable content.

Affected components

• List dropdown
• Calendar (year list)

Benefits

• Improved list dropdown performance with ability to render very large lists of options

Caveats

• A potential access point for technical debt if we expose to consumers for any content
• Many edge cases to solve