Geofencing with javascript

I want to use the Geofencing service with Maps SDK for Web (JS), I have found all the APIs to use but confused about how to use it with maps to make it user friendly. Basically I want to recreate the “Geofence Creator” in my application (Angular). Is there any blog for the same?

Which features do you want to have? Ability to draw fences by user in the application? Or just to show them?
Geofences creator source code is available on github: GitHub - tomtom-international/geofences-creator

I want ability to draw fences by user.