Stop partial Postback of Form using Javascript

javaScript to stop partial postback of form.

    $(document).ready(function () {

            $("form").submit(function (e) {

                var prm = Sys.WebForms.PageRequestManager.getInstance();

                var v = prm.get_isInAsyncPostBack()

                if ($("#txt").val() == "1") {

                    prm.abortPostBack();

                }

            })

     })

HTML :

       <asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>

        <asp:UpdatePanel ID="UpdatePanel1" runat="server">

            <ContentTemplate>

                <input type="text" id="txt" />

                <asp:Button ID="btn" runat="server" CssClass="temp" Text="Click" />

            </ContentTemplate>

        </asp:UpdatePanel>