code: function(d, fields, txt) {
      for (var k in d) {
        var t = txt;
        if (isNaN(k)) {
          t += txt ? '.' : '';
          t += k;
        }
  
        if ('object' === typeof d[k]) {
          fields = this.buildFieldByStep(d[k], fields, t);
        } else {
          switch (k) {
          case 'text':
          case 'type':
          case 'label':
            fields.push(t);
            break;
          }
        }
      }
      return fields;
    }
docs: Looking for Text, Type and label