code: function(from, to) {
          var classes = ($(from).attr('class') || '').replace(this.options.filterClasses, '').trim();
  
          if (classes) {
              $(to).addClass(classes);
          }
      }
docs: Copy classes from one element to another, but do not copy `filterClasses` classes.
  
  @param {jQuery} from
  @param {jQuery} to