Standard-style event object used by the Worker event system.

Whether the event participates in bubbling through an event-target hierarchy.

Whether preventDefault() can cancel this event.

Event target whose listener is currently being invoked. It is null outside listener dispatch.

true when preventDefault() successfully canceled the event's default action.

Event target on which the event was originally dispatched. It is null before dispatch.

Event type supplied when the event was created, for example message or error.