nsIDOMEvent
nseventptr getinternalnsevent(); violates the xpcom interface guidelines boolean getpreventdefault(); deprecated since gecko 16.0 void initevent(in domstring eventtypearg, in boolean canbubblearg, in boolean cancelablearg); boolean isdispatchstopped(); violates the xpcom interface guidelines void preventbubble(); obsolete since gecko 24 void preventcapture(); obsolete since gecko 24 void preventdefault(); void serialize(in ipcmessageptr am...
... return value getpreventdefault() note: use the defaultprevented attribute instead.
... boolean getpreventdefault(); parameters none.

CustomEvent - Web APIs
obsolete methods event.getpreventdefault() non-standard; use event.defaultprevented instead.

Event.defaultPrevented - Web APIs
note: you should use this instead of the non-standard, deprecated getpreventdefault() method (see bug 691151).

Event - Web APIs
event.getpreventdefault() returns the value of event.defaultprevented.