Resume Javascript Timer from database value

Question

I want to resume the timer from the last saved value in database in my online test series portal. Format of storing time is in "hh:mm:ss". Timer has been implemented using javascript. I am storing the last time to a session and assigning it to a label based on condition. If the session is found to be null, the default time is taken for the corresponding paper. How do I resume the timer for the last saved time for a paper which is resumed ? I am attaching my javascript code of timer :

 

<script type="text/javascript">

var myVar = setInterval(function () { myTimer() }, 1000);

var d = new Date();

var starttime = document.getElementById("<%= lbl_total_time.ClientID %>").innerHTML;

if (parseInt(starttime) < 10) {

starttime = "0" + starttime;

}

else {

starttime = starttime;

}

d.setHours(00, (parseInt(starttime) - 1), 59, 00);

function myTimer() {

if (d.getSeconds() <= 1)

d.setMinutes(d.getMinutes() - 1, 59, 00);

var h = d.getHours();

var m = d.getMinutes();

var s = d.getSeconds() - 1;

if (h == 0 && m == 0 && s == 1) {

document.getElementById("<%= lbsendintime.ClientID %>").innerHTML = "00:00:00";

}

else {

if (h < 10) {

h = "0" + h;

}

if (m < 10) {

m = "0" + m;

}

if (s < 10) {

s = "0" + s;

}

document.getElementById("<%= lbsendintime.ClientID %>").innerHTML = h + ":" + m + ":" + s;

d.setMinutes(m, s);

}

}

</script>

 

.... Here, in the above code, field 'lbl_total_timer' is the label to which time is assigned from database. 'Thanks in advance...