code: function ( selector ) {
              var el = this.element(),
                  children = el.children;
      
              if ( typeof selector === 'string' ) {
                  var elNum = children.length, result = [], i;
      
                  for ( i = 0; i < elNum; ++i ) {
                      var child = children[i],
                          match = $B.selector.match( child, selector );
      
                      if ( match ) result.push( child );
                  }
                  return result;
              } else {
                  //this.element().childNodes;
                  return $B( children ).toArray();
              }
          }
docs: 타겟타입:(Selector, Element)<br>
  target의 자식노드들;
  @return	{Array}