code: function () {
              this._handler = $B.bind(function (e) {
                  //DONE
                  if ( this.xhr.readyState !== 4 ) return false;
                  var evt = {target: this, xml: this.xhr.responseXML, text: this.xhr.responseText, status: this.xhr.status, statusText: this.xhr.statusText, data: this._data};
      
                  if ( this.xhr.status == 200 ) {
                      this.dispatch( 'complete', evt );
                  } else {
                      this.dispatch( 'error', evt );
                  }
      
                  this._removeEvents();
              }, this);
      
              //"Microsoft.XMLHTTP", "MSXML2.XMLHTTP.3.0"는 readyState 3를 지원하지 않는다.
              var i, activeXids = ['MSXML2.XMLHTTP.6.0', 'MSXML3.XMLHTTP', 'Microsoft.XMLHTTP', 'MSXML2.XMLHTTP.3.0'],
                  activeXidNum = activeXids.length;
      
              if ( window.XMLHttpRequest ) {
                  this.xhr = new XMLHttpRequest();
              } else {
                  for ( i = 0; i < activeXidNum; ++i ) {
                      try {
                          this.xhr = new ActiveXObject( activeXids[i] );
                          break;
                      } catch (e) {}
                  }
              }
          }
docs: ===============	Private Methods =============== //