JQuery issue after partial postback

I came to know this theory after much R&D. I was not aware why JQuery is not get fired after partial postback. Then from google, I found solution as below. We have to register JQuery events after end of partial postback.

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

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

            <ContentTemplate>

                <asp:Button ID="btn" Text="Test" runat="server" OnClick="btn_Click" />

                <input type="button" value="check" id="btncheck" />

            </ContentTemplate>

        </asp:UpdatePanel>

<script>

        Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(beginRequestHandler)

        Sys.WebForms.PageRequestManager.getInstance().add_endRequest(endRequestHandler)

        function beginRequestHandler() {

            var btn = document.getElementById('<%= btn.ClientID %>');

            btn.disabled = "disabled";

        }

        function endRequestHandler() {

            var btn = document.getElementById('<%= btn.ClientID %>');

            btn.disabled = "";

            register();

        }

        $(document).ready(function () {

            register();

        });

        function register()

        {

            $("#btncheck").click(function () {

                alert("Hello");

            });

        }

    </script>