How to create a countdown timer using C# and ASP.NET AJAX

Please check the below sample:

In .aspx page 

<div id="timelabel"></div>
 <script type="text/javascript">

var leave =<%=seconds %>;


CounterTimer();
var interv=setInterval(CounterTimer,1000);


function CounterTimer()
{
var day = Math.floor(leave / ( 60 * 60 * 24))
var hour = Math.floor(leave / 3600) - (day * 24)
var minute = Math.floor(leave / 60) - (day * 24 *60) - (hour * 60)
var second = Math.floor(leave) - (day * 24 *60*60) - (hour * 60 * 60) - (minute*60)


hour=hour<10 ? "0" + hour : hour;
minute=minute<10 ? "0" + minute : minute;
second=second<10 ? "0" + second : second;


var remain=day + " days   "+hour + ":"+minute+":"+second;
leave=leave-1;


document.getElementById("timelabel").innerText=remain;


}






 
In .aspx page.cs

    public double seconds;
    protected void Page_Load(object sender, EventArgs e)
    {
        seconds = (GetEndTime() - GetStartTime()).TotalSeconds;


    }
    private DateTime GetStartTime()
    {
        return DateTime.Now;
    }
    private DateTime GetEndTime()
    {
        return new DateTime(2008, 7, 23, 8, 10, 0);
    }