Refer below Sample for Your reference.
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script type="text/javascript">
function GetFooterValue() {
var dataGrid = document.getElementById("<% =CNclassification.ClientID %>");
var textbox = dataGrid.getElementsByTagName("INPUT");
var textarea = dataGrid.getElementsByTagName("TEXTAREA");
var txt_cramt;
var txt_reason;
for (var i = 0; i < textbox.length; i++) {
//Find the TextBox control by checking Id.
if (textbox[i].id.indexOf("txt_cramt") != -1) {
// code to access textbox value
txt_cramt = textbox[i].value;
}
}
for (var i = 0; i < textarea.length; i++) {
//Find the TEXTAREA control by checking Id.
if (textarea[i].id.indexOf("txtreason") != -1) {
// code to access TEXTAREA value
txt_reason = textarea[i].value;
}
}
alert("Value of cramt :" + txt_cramt + " and reason " + txt_reason);
};
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DataGrid ID="CNclassification" runat="server" Width="1112px" CssClass="ctrlNormal"
BackColor="White" HorizontalAlign="Justify" BorderStyle="None" BorderWidth="1px"
AllowSorting="True" HeaderStyle-Wrap="false" BorderColor="#E7E7FF" ShowFooter="True"
CellPadding="3" HeaderStyle-BackColor="LightGrey" HeaderStyle-Font-Bold="true"
AlternatingItemStyle-BackColor="Linen" AutoGenerateColumns="False" GridLines="Both">
<SelectedItemStyle Font-Bold="True" ForeColor="#F7F7F7" BackColor="#738A9C"></SelectedItemStyle>
<EditItemStyle BackColor="#F7F7F7"></EditItemStyle>
<AlternatingItemStyle BackColor="#F7F7F7"></AlternatingItemStyle>
<ItemStyle ForeColor="#4A3C8C" BackColor="#E7E7FF"></ItemStyle>
<HeaderStyle Font-Bold="True" Wrap="False" ForeColor="#F7F7F7" BackColor="#0d337f">
</HeaderStyle>
<FooterStyle ForeColor="#4A3C8C"></FooterStyle>
<Columns>
<asp:TemplateColumn HeaderText="Sl No" HeaderStyle-Width="5%">
<ItemTemplate>
<asp:Label ID="Label1" runat="server" CssClass="ctrlNormal" Width="100%" Text='<%# DataBinder.Eval(Container, "DataItem.iSNo") %>'>
</asp:Label>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="Requested Amt" HeaderStyle-Width="10%">
<ItemStyle HorizontalAlign="Right"></ItemStyle>
<ItemTemplate>
<asp:Label ID="lbl_cramt" runat="server" Style="text-align: right" CssClass="ctrlNormal"
Width="100%" Text='<%# DataBinder.Eval(Container, "DataItem.mRequested_amt") %>'>
</asp:Label>
</ItemTemplate>
<FooterStyle HorizontalAlign="Right"></FooterStyle>
<FooterTemplate>
<asp:TextBox ID="txt_cramt" Style="text-align: right" runat="server" Width="100%"></asp:TextBox>
</FooterTemplate>
<EditItemTemplate>
<asp:TextBox ID="txt_cramt1" Style="text-align: right" runat="server" CssClass="ctrlNormal"
OnBlur="CheckCNAmount();" onkeydown="return jsDecimals(event);" Width="100%"
Text='<%# DataBinder.Eval(Container, "DataItem.mRequested_amt") %>'>
</asp:TextBox>
</EditItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="Reason For Credit Note" HeaderStyle-Width="50%">
<ItemTemplate>
<asp:Label ID="lblreason" runat="server" CssClass="ctrlNormal" Width="100%" Text='<%# DataBinder.Eval(Container, "DataItem.vcRemark") %>'>
</asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:TextBox ID="txtreason" runat="server" CssClass="ctrlNormal_NoW" Width="100%"
Height="45px" TextMode="MultiLine"></asp:TextBox>
</FooterTemplate>
<EditItemTemplate>
<asp:TextBox ID="txtreason1" runat="server" TextMode="MultiLine" CssClass="ctrlNormal"
Width="100%" Text='<%# DataBinder.Eval(Container, "DataItem.vcRemark") %>'>
</asp:TextBox>
</EditItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>
<br />
<input id="btnGetValues" type="button" value="Get Footer value" onclick="GetFooterValue()" />
<br />
<br />
</div>
</form>
</body>
</html>
C#
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[3] { new DataColumn("iSNo",typeof(string))
,new DataColumn("mRequested_amt",typeof(string))
,new DataColumn("vcRemark",typeof(string))
});
dt.Rows.Add("1", "100", "Remark 1");
dt.Rows.Add("2", "200", "Remark 2");
dt.Rows.Add("3", "300", "Remark 3");
dt.Rows.Add("4", "400", "Remark 4");
CNclassification.DataSource = dt;
CNclassification.DataBind();
VB.Net
Dim dt As DataTable = New DataTable()
dt.Columns.AddRange(New DataColumn(2) {New DataColumn("iSNo", GetType(String)), New DataColumn("mRequested_amt", GetType(String)), New DataColumn("vcRemark", GetType(String))})
dt.Rows.Add("1", "100", "Remark 1")
dt.Rows.Add("2", "200", "Remark 2")
dt.Rows.Add("3", "300", "Remark 3")
dt.Rows.Add("4", "400", "Remark 4")
CNclassification.DataSource = dt
CNclassification.DataBind()
Screenshot
