问在PostBack上触发必需的字段验证器

EN

<textarea style="width: 380px" id="txtAdditonalEmail" runat="server" rows="5"></textarea>
<asp:RequiredFieldValidator ID="rfvAdditonal" runat="server" ControlToValidate="txtAdditonalEmail" 
ErrorMessage="Atleast one additonal email is required"  ForeColor="Red" ValidationGroup="vldRequest"></asp:RequiredFieldValidator>

<asp:FileUpload ID="fluCsr" runat="server"  />

function ValidateFileUpload() {
            var fuData = document.getElementById('<%= fluCsr.ClientID %>');
            var FileUploadPath = fuData.value;
            var Extension = FileUploadPath.substring(FileUploadPath.lastIndexOf('.') + 1).toLowerCase();
            var lblMsg = $("#<%= lblMsg.ClientID %>");
            var btnRead = $("#<%=txtComments.ClientID %>");

            if (Extension != "txt" && Extension != "csr" && Extension != "pem") {
                if (lblMsg != null && btnRead != null) {
                    lblMsg.show();
                }
            }
            else {
                lblMsg.hide();
                this.$("#form1").submit();
            }

        }