DWR回调函数和生成上拉列表

DWR回调函数和生成下拉列表
         /**
* DWR 测试会议室
*/
    function checkMeetingRoom(){
       var starttime = meetingForm.startdate.value;
       var endtime = meetingForm.enddate.value;
       var meetingRoom = meetingForm.meetingRoomName.value;
       if(starttime != "" && endtime != ""){
          MeetingDWR.checkMeetingRoom      (starttime,endtime,callMeetingRoom);
       }
    }
    function callMeetingRoom(result) {
        objNew=document.getElementById("meetingRoomCheck");
    if(result.length == 0){
       objNew.innerHTML = "没有可用会议室,请重新安排时间！";
           clearOption();
           var objTotal = document.meetingForm.meetingRoomName;
           var optionTotal = new Option('--不可选--', "-1");
           objTotal.options.add(optionTotal);
           return false;
    }
    else{
      clearOption();
      objNew.innerHTML = "";
      var objFirst = document.meetingForm.meetingRoomName;
          var optionFirst = new Option('--请选择--', "-1");
          objFirst.options.add(optionFirst);
  for(var i = 0; i<result.length; i++) {
       var obj = document.meetingForm.meetingRoomName;
               var option = new Option(result[i], result[i]);
               obj.options[i+1] = option;
           }
}
    }
    //清空下拉列表
    function clearOption(){
var obj = document.meetingForm.meetingRoomName;
var len = obj.options.length;
        for(var i = 0; i < len; i++) {
            obj.options[0] = null;
          }
  }