日期控件判断是否为空

<input type="text" class="input-text inline" style="width:120px;" id="beginDateSel" name="beginDateSel" placeholder=" 起始日期" value="${query.beginDate?then(query.beginDate?date,'')}" onClick="WdatePicker()">

 <input type="text" class="input-text inline" style="width:120px;" id="endDateSel" name="endDateSel" placeholder=" 结束日期" value="${query.endDate?then(query.endDate?date,'')}" onClick="WdatePicker()">