Calender with month and year only

var cal1;
                  var cal2;

                  function pageLoad() {
                      cal1 = $find("calendar1");
                      cal2 = $find("calendar1");

                      modifyCalDelegates(cal1);
                      modifyCalDelegates(cal2);
                  }

                  function modifyCalDelegates(cal) {
                      //we need to modify the original delegate of the month cell.
                      cal._cell$delegates = {
                          mouseover: Function.createDelegate(cal, cal._cell_onmouseover),
                          mouseout: Function.createDelegate(cal, cal._cell_onmouseout),

                          click: Function.createDelegate(cal, function(e) {
                              ///
                              /// Handles the click event of a cell
                              ///
                              /// The arguments for the event
                              //  e.stopPropagation();
                              e.preventDefault();

                              if (!cal._enabled) return;

                              var target = e.target;
                              var visibleDate = cal._getEffectiveVisibleDate();
                              Sys.UI.DomElement.removeCssClass(target.parentNode, "ajax__calendar_hover");
                              switch (target.mode) {
                                  case "prev":
                                  case "next":
                                      cal._switchMonth(target.date);
                                      break;
                                  case "title":
                                      switch (cal._mode) {
                                          case "days": cal._switchMode("months"); break;
                                          case "months": cal._switchMode("years"); break;
                                      }
                                      break;
                                  case "month":
                                      //if the mode is month, then stop switching to day mode.
                                      if (target.month == visibleDate.getMonth()) {
                                          this._switchMode("days");
                                      }
                                      else {
                                          cal._visibleDate = target.date;
                                          this._switchMode("days");
                                      }
                                      cal.set_selectedDate(target.date);
                                      cal._switchMonth(target.date);
                                      cal._blur.post(true);
                                      cal.raiseDateSelectionChanged();
                                      break;
                                  case "year":
                                      if (target.date.getFullYear() == visibleDate.getFullYear()) {
                                          cal._switchMode("months");
                                      }
                                      else {
                                          cal._visibleDate = target.date;
                                          cal._switchMode("months");
                                      }
                                      break;

                                  case "day":
                                      this.set_selectedDate(target.date);
                                      this._switchMonth(target.date);
                                      this._blur.post(true);
                                      this.raiseDateSelectionChanged();
                                      break;
                                  case "today":
                                      cal.set_selectedDate(target.date);
                                      cal._switchMonth(target.date);
                                      cal._blur.post(true);
                                      cal.raiseDateSelectionChanged();
                                      break;

                              }

                          })
                      }

                  }

                  function onCalendarShown(sender, args) {
                      //set the default mode to month
                      sender._switchMode("months", true);
                      changeCellHandlers(cal1);
                  }


                  function changeCellHandlers(cal) {

                      if (cal._monthsBody) {

                          //remove the old handler of each month body.
                          for (var i = 0; i < cal._monthsBody.rows.length; i++) {
                              var row = cal._monthsBody.rows[i];
                              for (var j = 0; j < row.cells.length; j++) {
                                  $common.removeHandlers(row.cells[j].firstChild, cal._cell$delegates);
                              }
                          }
                          //add the new handler of each month body.
                          for (var i = 0; i < cal._monthsBody.rows.length; i++) {
                              var row = cal._monthsBody.rows[i];
                              for (var j = 0; j < row.cells.length; j++) {
                                  $addHandlers(row.cells[j].firstChild, cal._cell$delegates);
                              }
                          }
                      }
                  }
                  function onCalendarHidden(sender, args) {
                      //
                      //
                      if (sender.get_selectedDate()) { //
                          if (cal1.get_selectedDate() && cal2.get_selectedDate() && cal1.get_selectedDate() > cal2.get_selectedDate()) {
                              alert('The "From" Date should smaller than the "To" Date, please reselect!');
                              sender.show();
                              return;
                          }
                          //get the final date;
                          var finalDate = new Date(sender.get_selectedDate());
                          var selectedMonth = finalDate.getMonth();
                          finalDate.setDate(1);
                          if (sender == cal2) {
                              // set the calender2's default date as the last day
                              finalDate.setMonth(selectedMonth + 1);
                              finalDate.format(sender._format);
                              finalDate = new Date(finalDate - 1);
                          }
                          //  document.getElementById('').value = finalDate.format("MMM/YYYY");
                          document.getElementById('').value = finalDate.format(sender._format);
                      }
                  }

OnClientShown="onCalendarShown"                                        OnClientHidden="onCalendarHidden" BehaviorID="calendar1" DefaultView="Months" Format="MMM/yyyy"