code: function (e) {
                      var evt = {
                          _event: e,			//실제 이벤트 객체
                          type: originToCrossType( e.type ),
                          target: e.target,
                          currentTarget: e.currentTarget,
                          relatedTarget: e.relatedTarget,
                          eventPhase: e.eventPhase,
                          //마우스 좌표
                          layerX: e.layerX, layerY: e.layerX,//파폭
                          clientX: e.clientX, clientY: e.clientY,
                          pageX: e.pageX, pageY: e.pageY,
                          offsetX: e.offsetX, offsetY: e.offsetY,
                          screenX: e.screenX, screenY: e.screenY,
                          shiftKey: e.shiftKey, charCode: e.charCode,
                          altKey: e.altKey,
                          ctrlKey: e.ctrlKey,
                          //이벤트 관리 함수
                          stopPropagation: function () { if (this._event) this._event.stopPropagation(); },
                          preventDefault: function () { if (this._event) this._event.preventDefault(); },
                          //mousewheel
                          delta: 0,
                          data: e.customData || data
                      };
      
                      /*
                       mousewheel delta
                       trace( 'detail:' + e.detail );//FF, Oprera
                       trace( 'wheelDelta:' + e.wheelDelta );//IE, Chrome, Safari, Opera
                       */
                      if ( e.wheelDelta ) {
                          evt.delta = e.wheelDelta / 120;
                      } else if ( e.detail ) {
                          evt.delta = -e.detail / 3;
                      }
      
                      handler.call( el, evt );
                  }
docs: 중첩된 함수를 정의하고 이 함수를 handler 함수 대신 등록한다.