code: function() {
          var child;
          var root = this.vectorRoot;
          if (root) {
              while (child = root.firstChild) {
                  root.removeChild(child);
              }
          }
          root = this.textRoot;
          if (root) {
              while (child = root.firstChild) {
                  root.removeChild(child);
              }
          }
          if (this.indexer) {
              this.indexer.clear();
          }
      }
docs: Method: clear
  Remove all the elements from the root