Web Map Legend - only show filtered items or items in view extent

[AutumnMason]

Not sure if this has been mentioned before, but I would really like to be able to use the same function that I am able to use in ArcGIS Layout View, where I can check to only display items in the TOC that are checked, or to only show items that are in the map extent. Right now in a web map, even after I filter, all of the items still show in the TOC and legend. I can somewhat bypass this by dragging all of the icons I don't want to show up in the legend of a web map/app under the Other option in the Change Style (Unique symbols) menu, but with over 30 items, this process is cumbersome.

For example, see pic. If I only want to show Campground Camping, I will have to move all of the other legends under Other so that they don't show. Is there a better workaround than what I am using? Or can this be added as new functionality?

Thanks

[KDCGIS]

I'd regard this as a necessary feature.  For feature layers used differently in different maps/apps we need to have flexibility in what the legend shows.  We can workaround for my current map at the ArcGIS Pro level/adding a more customised service, but to me AGOL needs this functionality.

[RobertKirkwood]

Can this be done in JavaScript using the Legend widget? 

[BenLeslie2]

I am also trying to filter the legend by map extent on ArcGIS Online (specifically Dashboards and/or Web App builder for developers) - was there any progress on this?

[jbelak_audubon]

Some service layers like PAD-US cannot be included when using the Analysis Widget. They completely take over the available space in the .pdf report map legend with categories that don't even exist in the map view. This could be solved by making the legend filter by view extent. There is never any need to have categories in the legend that are not in the view extent, so why is this behavior the default?