Description:
We use a feature service in our ArcGIS Enterprise Portal where a layer contains more than 100 subtypes. In both the Map Viewer’s editing widget and ArcMaps SDK for Javascript 4.x, all subtype names are currently displayed in a flat, non-hierarchical list.
With a large number of subtypes, this leads to significant usability issues:
- The list becomes difficult to navigate and visually cluttered
- Finding specific entries is inefficient
- There is no way to control or customize the sorting/order of subtype values

In ArcGIS Pro, the subtype list is collapsible. In “Create Features” mode, the layer is displayed with its associated subtype names, and the list can be expanded or collapsed using a dropdown control.

The Map Viewer and ArcMaps SDK for JavaScript contain a combobox in the edit-widget feature-form for the subtype attribute.

Proposed enhancement:
I suggest improving the subtype selection UI by introducing:
- collapsible lists;
- a searchable combobox/dropdown instead of a static list; and
- support for custom sorting of subtype values (by code or by name, in ascending or descending order).