javascript在Asp.net验证上传文件的文件类型的

<%@ Page Language="C#" MasterPageFile="~/VQPMaster.master" AutoEventWireup="true" CodeFile="importQuotation.aspx.cs" Inherits="ImportExcel_importQuotation" Title="Untitled Page" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolderMain" Runat="Server">
    <script type="text/javascript" src="../js/jquery-1.5.2.js"></script>
    <script language="javascript" type="text/javascript">
        
        $(document).ready(function(){
            var fileUpload = $("#<%=fileUpload.ClientID%>");
            var txtEmail = $("#<%=txtEmail.ClientID%>");
            var lblMessage = $("#<%=lblMessage.ClientID%>");
            lblMessage.text();
            $("#<%=btnSubmit.ClientID%>").click(function(){
                 if(fileUpload.val() == ""){
                    fileUpload.focus();
                    lblMessage.text("please upload file!");
                    return false;
                }
                else // valid the upload file extension file name!
                {
                  var hash = {
                      '.XLS'  : 1,
                      '.XLSX' : 1
                  };
                  var re = /\..+$/;
                  var ext = fileUpload.val().toUpperCase().match(re);
                  if (!hash[ext]) {
                    lblMessage.text("Invalid filename, please select another file!");
                    return false;
                  }   
                }
                if(txtEmail.val() == ""){
                    lblMessage.focus();
                    lblMessage.text("please input user email!");
                    return false;
                }
               
                               
            })
            $("#btnReset").click(function(){
                 lblMessage.text("")               
            })
         })
    </script>
   
    <div id = "divUploadMain" style =" margin : 5px 0px 0px 4%; ">
        <div id= "divFileUpload" style="height : 30px; margin-bottom : 5px;" >
            Quote&nbsp;&nbsp;&nbsp;&nbsp;File&nbsp;:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
            &nbsp;&nbsp;&nbsp;&nbsp;<asp:FileUpload ID="fileUpload" runat="server" Width="464px" />
        </div>
        <div id = "divEmail" style="height : 30px; margin-top : 5px;">
            MAPS&nbsp;Email&nbsp;contact&nbsp;:
            <asp:TextBox ID="txtEmail" runat="server" Width="464px"></asp:TextBox>
        </div>
        <div id="divBtns">
            <asp:Button ID="btnSubmit" runat="server" Text="Submit"  />&nbsp;
            <input id="btnReset" type="reset" value="Reset" />&nbsp;
            <asp:Label ID="lblMessage" runat="server" ForeColor="Red" Visible="true" Text=""></asp:Label></div>
    </div> 
</asp:Content>