WdatePicker开始日期不能大于结束日期

开始日期：<input class="startDate Wdate" id="startDate" type="text" onfocus="WdatePicker({dateFmt:'yyyy-MM-dd',maxDate:'#F{$dp.$D(\'endDate\')}'})" />
结束日期：<input class="endDate Wdate" id="endDate" type="text" onfocus="WdatePicker({dateFmt:'yyyy-MM-dd',minDate:'#F{$dp.$D(\'startDate\')}',maxDate:'2120-10-01'})" />