F.js判断下拉列表是否为0

<ext:DropDownList ID="DDLReviewPerson" Label="工艺卡审核人" runat="server" DataTextField="RealName" EnableEdit="true" ForceSelection="true"
AutoSelectFirstItem="false" DataValueField="UserName" Required="true" ShowRedStar="true"/>

if (DDLReviewPerson.F_Items.Count == 0)
{
　　Alert.Show("当前项目未设置工艺卡审核人,请联系项目负责人进行配置！");
}