Calculate square feet online in map viewer

[DavinShokes1]

In Collector for Arcgis a polygon feature's popup shows the area as defines in the service definition.  However, there does not appear to be a way to see the area of a feature in map viewer or a web appbuilder app which means manually entering the area is not possible.

Ultimately, I'm trying to populate fields with acreage and sqft without using ArcMap or pro. I've tried field calculator without success.

[SethLewis1]

You'd have to record/input into a field the area for each polygon in your dataset manually but WAB has a Measurement tool that'll allow for you to select Acres or Sq. Ft.

[DavinShokes1]

Thanks for the suggestion Seth. I tested with the AppBuilder widget and was unable to measure existing features. It only measures manually drawn graphics. Snapping the measurement is possible by holding control, but it is not a quick process for irregular shapes.

[RussRoberts · Accepted solution]

There is a sample in the JS 4.0 beta with popups with the measure action.

Define custom Popup actions | ArcGIS API for JavaScript