Calling Server side Method From Javascript

 <script type="text/javascript">
        function HandleIT() {
            var name = document.getElementById('<%=txtname.ClientID %>').value;
            var address = document.getElementById('<%=txtaddress.ClientID %>').value;
            PageMethods.ProcessIT(name, address, onSucess, onError);
            function onSucess(result)
            {
                alert(result);
            }
            function onError(result)
            {
                alert('Something wrong.');
            }
        }
    </script>

<div>
        <p>Say bye-bey to Postbacks.</p>

        <asp:ScriptManager ID='ScriptManager1' runat='server' EnablePageMethods='true' />
<div>
        <asp:TextBox ID="txtname" runat="server"></asp:TextBox>
        <br />
        <asp:TextBox ID="txtaddress" runat="server"></asp:TextBox>
        <br />
        <asp:Button ID="btnCreateAccount" runat="server" Text="Signup" OnClientClick="HandleIT(); return false;" />
    </div>

[WebMethod]
    public static string ProcessIT(string name, string address)
    {
        string result = "Welcome Mr. " + name + ". Your address is '" + address + "'.";
        return result;
    }

http://codes.codedigest.com/CodeDigest/80-Calling-a-Serverside-Method-from-JavaScript-in-ASP-Net-AJAX---PageMethods.aspx


http://aspdotnetcodebook.blogspot.in/2008/10/calling-page-methods-from-javascript.html