This feature has been deprecated. Use !up.emit(type).defaultPrevented instead.
!up.emit(type).defaultPrevented
Load unpoly-migrate.js to polyfill deprecated features.
unpoly-migrate.js
Emits an event and returns whether no listener has prevented the default action.
if (up.event.nobodyPrevents('disk:erase')) { Disk.erase() })
whether no listener has prevented the default action
