Arguments for the
The optional object that will be sent to the
upload handler in the form of key/value pairs.
The list of the files that were uploaded or removed.
The headers of the request.
true if the event was prevented
by any of its subscribers.
true if the default action was prevented. Otherwise, returns
Prevents the default action for a specified event.
In this way, the source component suppresses the built-in behavior that follows the event.