ENTER按键上的DropDownList回发未触发服务器端事件

$(document).ready(function() {
  $('body').on('keydown', function(e) {
    if (e.which === 13) {
      // 触发服务器端事件
      // 例如：__doPostBack('DropDownList1', '');
      e.preventDefault();
      return false;
    }
  });
});

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
  <asp:ListItem Text="Option 1" Value="1"></asp:ListItem>
  <asp:ListItem Text="Option 2" Value="2"></asp:ListItem>
</asp:DropDownList>

$(document).ready(function() {
  $('body').on('keydown', function(e) {
    if (e.which === 13) {
      var selectedValue = $('#DropDownList1').val();
      $.ajax({
        url: '/Controller/Action',
        type: 'POST',
        data: { selectedValue: selectedValue },
        success: function(result) {
          // 处理服务器端返回的结果
        }
      });
      e.preventDefault();
      return false;
    }
  });
});