code: function(response, status, xhr) {
          var url = xhr.url;
  
          // Remove loading state
          this.element
              .removeClass('is-loading')
              .aria('busy', false);
  
          // Clear cache
          delete this.cache[url];
  
          // HTML
          if (xhr.getResponseHeader('Content-Type').indexOf('text/html') >= 0) {
              if (xhr.cache) {
                  this.cache[url] = response;
              }
  
              this.position(response);
  
          // JSON, others
          } else {
              this.process(response);
          }
      }
docs: Event handler for AJAX `done` events when called through `requestData()`.
  
  @param {String} response
  @param {String} status
  @param {jQuery.ajax} xhr