function fetchData(url, options, cb){

  if(!cb) throw new Error('Please suply a callback function!');

  if(!fetchData._cache) fetchData._cache = {};

  var settings = {
    method: "GET",
    url: url
  }

  extend(settings, options);

  if(!fetchData._cache[url]){
    $.ajax(settings)
      .done(function(data){
        fetchData._cache[url] = data;
        cb(null,data);
      })
      .fail(function(jqXHR, textStatus, errorThrown){
        var errData = {
          jqXHR: jqXHR,
          textStatus:textStatus,
          errorThrown:errorThrown
        };
        cb(errData, null);
      })
  } else{
    cb(null,fetchData._cache[url]);
  }

}