How to get the return value of the event listener keyboardframechanged ?

In this link Titanium.App-event-keyboardframechanged it says that : " The event returns the dictionary containing keyboardFrame.x", I am new in programming so I want to know how to get keyboardFrame.width from this event, here is the code:

Ti.App.addEventListener("keyboardframechanged",function(e){alert("keyboard changed");});