docs: function filterByThreshold(nodeModel, totalArea, sum, orderBy, orderedChildren) {
  
      // visibleMin is not supported yet when no option.sort.
      if (!orderBy) {
          return sum;
      }
  
      var visibleMin = nodeModel.get('visibleMin');
      var len = orderedChildren.length;
      var deletePoint = len;
  
      // Always travel from little value to big value.
      for (var i = len - 1; i >= 0; i--) {
          var value = orderedChildren[
              orderBy === 'asc' ? len - i - 1 : i
          ].getValue();
  
          if (value / sum * totalArea < visibleMin) {
              deletePoint = i;
              sum -= value;
          }
      }
  
      orderBy === 'asc'
          ? orderedChildren.splice(0, len - deletePoint)
          : orderedChildren.splice(deletePoint, len - deletePoint);
  
      return sum;
  }