JSONP Snipp

ajax.jquery.js

Since you use JSONP, you should code it like this IMHO :

$.ajax(URL, {
    crossDomain:true, 
    dataType: "jsonp", 
    success:function(data,text,xhqr){
        $.each(data, function(i, item) {
            alert(item);
        });
    }
});
The correct parameter is callback but jQuery generates one automagically so dont specify it.