动态添加下拉列表中的值

function   enter(){   //下拉列表得onChange
    var compid = $F('store');
        var url = '/workperformance/MyHolidayModel.jsp';
var pars = 'compid=' + compid;
var myAjax = new Ajax.Request(url, {method: 'get', parameters: pars, onComplete: showResponse});

  }
  function showResponse(originalRequest) {
var resText = originalRequest.responseText.evalJSON();
//$('dept').value = resText.personInfo[0].depcname;
$('dept').options.length = 1;
var count = resText.personInfo.length;
for(var i = 0; i < count; i++) {
var dep = resText.personInfo[i];
var newOption = document.createElement("OPTION");
newOption.value = dep.depid;
newOption.text = dep.depcname;
$('dept').add(newOption);
}
//alert(resText.personInfo[0].depcname);
///$('dept').value = resText.personInfo[0].depid;
}