easyui datebox 时间限制，datebox开始时间限制结束时

<tr> 
 <td width="15%" class="label">合同起始日期:</td> 
 <td width="35%"> 
 <input value="${loan.contractBegtime}" class="f1 easyui-datebox" id="contractBegtime" name="contractBegtime" data-options="required:true,editable:false"/> 
 <font class="star-red"></font> 
 </td> 
<td width="15%" class="label">合同截止日期:</td> 
<td width="35%"> 
 <input value="${loan.contractEndtime}" class="f1 easyui-datebox" id="contractEndtime" name="contractEndtime" data-options="required:true,editable:false"/> 
 <font class="star-red"></font> 
 </td> 
</tr> 

$("#contractBegtime").datebox({ 
 onSelect : function(beginDate){ 
  $('#contractEndtime').datebox().datebox('calendar').calendar({ 
   validator: function(date){ 
    return beginDate<date;//<= 
   } 
  }); 
 } 
});