You can easily use javascript for that.Get reference from Here
Or Replace your success code with following code:-
function winner(data)
{
domParser = new DOMParser();
var xmlDoc=domParser.parseFromString(data,"text/xml");
var _bookStore=[];
x$(xmlDoc).find("book").each(function(element,index){
var _book={};
_book.author=[];
_book.title=element.getElementsByTagName("title")[0].textContent;
for(j=0;j<element.getElementsByTagName("author").length;j++){
_book.author.push(element.getElementsByTagName("author")[j].textContent);
}
_book.year=element.getElementsByTagName("year")[0].textContent;
_book.price=element.getElementsByTagName("price")[0].textContent;
_bookStore.push(_book);
});
alert("hello"+JSON.stringify(_bookStore));
}