Call all controls value using JavaScript on Button click in ASP.Net

Hi Nagaraju,

I have created a sample that fullfill your requirement

HTML

<div>
    <asp:TextBox ID="TextBox1" runat="server" />
    <br />
    <asp:TextBox ID="TextBox2" runat="server" />
    <br />
    <asp:TextBox ID="TextBox3" runat="server" />
    <br />
    <asp:GridView ID="Gridview1" runat="server" AutoGenerateColumns="false">
        <Columns>
            <asp:TemplateField HeaderText="ID">
                <ItemTemplate>
                    <asp:TextBox Text='<%# Eval("Id") %>' runat="server"></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Header 2">
                <ItemTemplate>
                    <asp:TextBox Text='<%# Eval("LoanType") %>' runat="server"></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Header 3">
                <ItemTemplate>
                    <asp:TextBox Text='<%# Eval("LoanTerm") %>' runat="server"></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>
    <br />
    <asp:Button ID="btnSave" Text="Save" OnClientClick="return ClearAll()" runat="server" />
</div>
<div>
    <script type="text/javascript">
        function ClearAll() {
            document.getElementById("TextBox1").value = "";
            document.getElementById("TextBox2").value = "";
            document.getElementById("TextBox3").value = "";
            var rows = document.getElementById('Gridview1').getElementsByTagName('tr');
            for (var i = 1; i <= rows.length; i++) {
                if (rows.length > 1) {
                    document.getElementById('Gridview1').deleteRow(i);
                    i--;
                }
            }
            return false;
        }
    </script>
</div>

ScreenShot

Hope this works for you