Issue
Autofill effects multiple components and browsers don’t trigger the same event on inputs. If you want to validate a multiple input autofill like an address you don’t want to validate 4 times (street, city, state, zip). 4 events triggered for 4 inputs… What you want is a single autofill event from the browser with a list of the elements and values included in the event, right?
Suggestion
Browsers should trigger a global autofill event on the document, iframe, and/or window (discuss). Should the event be on an element too? I would think not because it can get confusing when you have multiple events for a single event.
Event should include a reference (target) to the elements impacted by the autofill as well as the autofill type (address, phone, username, etc…) and values. There could be an option to preventDefault() or an option to change the values before they are applied.