how to modify field contents in feature of a featureLayer by javascript code from a custom widget

MichaelLev

I'm developing custom widgets for WAB (Develper Edtion) 2.17, Launchpad Theme, on 3D Scenes (ArcGIS API for javascript 4.17), on our compamy portal (version 10.7.1).

I am still a newbie...

I need, from within javascript code of a custom widget, to modify and update contents of a field of some feature in a (editable, of course) feature layer. How do I do it?

Help will be greatly appreciated,

Michael