SyntheticEvent Reference

To access the underlying browser event for some reason, simply use the nativeEvent attribute to get it. The synthetic events are different from and do not map directly to the browser's native events. For example in onMouseLeave event.nativeEvent will point to a mouseout event.

SyntheticEvent properties and methods
Member
void preventDefault()
void stopPropagation()
boolean bubbles
boolean cancelable
boolean defaultPrevented
boolean isDefaultPrevented()
boolean isPropagationStopped()
boolean isTrusted
number eventPhase
number timeStamp
string type
DOMEventTarget target
DOMEventTarget currentTarget
DOMEvent nativeEvent

'target' is the element that triggered the event while 'currentTarget' is the element that has the event listener.

'relatedTarget' is used by some events to specify a secondary target. For instance, during focus events, target will be the element gaining focus, and relatedTarget will be the element losing focus.