code: function getResults( form, url, callback ){
      var formData = new FormData( form );
      var request = new XMLHttpRequest();
      request.open("POST", url);
      request.send(formData);
      
      request.onload = function(e) {
       if (request.status == 200) {
              callback(null, JSON.parse(request.responseText));
          } else {
              callback("Error " + request.status + ' - ' + request.responseText, null);
          }
      };
  }
docs: post form and returns JSON