I'm using a simple Arcade expression to return what I thought would be an single intersecting parcel polygon when a gravity main line feature was clicked on. In my short sightedness I hadn't realized it's possible for that gravity main line to exist across two parcels.
This is what I thought it would always return:

It turns out though I can get something like this where both parcel numbers are returned and it looks messy:

Is there a way I can format my return statement to display multiple parcels separated by a comma?
Here's my code:
var parcel = FeatureSetByName($map, 'Parcel Boundary')
var parcelID = Intersects(parcel, $feature)
var parcel_details = ''
for(var row in parcelID) {
parcel_details = parcel_details
+ row.PARCEL_ID
}
return parcel_details