How to use onFormSubmit( )

After the release of this new feature I want to give it a try but how does it work?

I want to use custom form to send information.

  1. It works with contact Form but is it possible to trigger that event with a custom form. is it possible to trigger it with wixdata or wixdataset insert/update

  2. Do I have to set up anything in the dashboard?

  3. It it possible to log text from event.js (for debugging) ? in site monitor maybe?

  4. Does the event fire in preview mode or only in published sites?

Many question that are not answered in the doc.

Speaking of the doc there is a difference between the function signature in the presentation and in exemplate

onFormSubmit(event: FormSubmitEvent) 
wixCrm_onFormSubmit(event)

which one is correct ? after some tests, wixCrm_onFormSubmit(event) is the correct one. Plz update the doc