Disabling the link which is placed in the footer of the gridview

I am trying to disable link when a the time is up. Is there anything I miss out? Like in this case I want to disable it when distance = 0.

See the markup below,

<FooterTemplate>
                                                        <asp:LinkButton ID="lnkInsert" ValidationGroup="INSERT" OnClick="lnkInsert_Click" runat="server">INSERT</asp:LinkButton>
                                                        <p id="demo"></p>
                                        <script>
                                            // Set the date we're counting down to
                                            var countDownDate = new Date("Sep 11, 2018 20:00:00").getTime();

                                            // Update the count down every 1 second
                                            var x = setInterval(function () {

                                                // Get todays date and time
                                                var now = new Date("Sep 11, 2018 20:00:00").getTime();

                                                // Find the distance between now and the count down date
                                                var distance = countDownDate - now;

                                                // Time calculations for days, hours, minutes and seconds
                                                var days = Math.floor(distance / (1000 * 60 * 60 * 24));
                                                var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
                                                var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
                                                var seconds = Math.floor((distance % (1000 * 60)) / 1000);

                                                // Output the result in an element with id="demo"
                                                document.getElementById("demo").innerHTML = days + "d " + hours + "h "
                                                    + minutes + "m " + seconds + "s ";

                                                // If the count down is over, write some text 
                                                if (distance <= 0) {
                                                    clearInterval(x);
                                                    document.getElementById("demo").innerHTML = "EXPIRED";
                                                    document.getElementById("lnkInsert").disabled = true;
                                                }
                                            }, 1000);
                                        </script>
                                                    </FooterTemplate>