Set TimeZone in AJAX CalendarExtender using C# and VB.Net in ASP.Net

Hi nauna,

Refer below sample.

HTML

<script type="text/javascript">
    function clientShowing(sender, args) {
        sender.set_todaysDate(new Date('<%= ToCalenderFormat(GetDatetimewithtimezone("MOUNTAIN STANDARD TIME"),GetTimeSpanDifference("MOUNTAIN STANDARD TIME")) %>'));
            sender.set_startDate('<%= ToCalenderFormat(GetDatetimewithtimezone("MOUNTAIN STANDARD TIME"),GetTimeSpanDifference("MOUNTAIN STANDARD TIME")) %>');
            sender.set_endDate('<%= ToCalenderFormat(GetDatetimewithtimezone("MOUNTAIN STANDARD TIME").AddDays(7),GetTimeSpanDifference("MOUNTAIN STANDARD TIME")) %>');
        }
</script>
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<asp:Label ID="lblb" runat="server"></asp:Label>
<asp:TextBox ID="txtDate" runat="server" CssClass="disable_future_dates" />
<asp:ImageButton runat="server" ID="imgPopup" ImageUrl="~/Calendar.png" />
<cc1:CalendarExtender ID="CalendarExtender1" runat="server" TargetControlID="txtDate"
    PopupButtonID="imgPopup" OnClientShowing="clientShowing" />

Code

C#

public static String ToCalenderFormat(DateTime dt, TimeSpan TimeZoneDifference)
{
    return new DateTimeOffset(dt.Ticks, TimeZoneDifference).ToString("yyyy-MM-ddTHH:mm:ssZ");
}
public static DateTime GetDatetimewithtimezone(string Timezone)
{
    return (TimeZoneInfo.ConvertTimeFromUtc(DateTime.UtcNow, TimeZoneInfo.FindSystemTimeZoneById(Timezone)));
}

public static TimeSpan GetTimeSpanDifference(string Timezone)
{
    TimeZoneInfo timeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById(Timezone);
    return timeZoneInfo.BaseUtcOffset;
}

VB.Net

Public Shared Function ToCalenderFormat(ByVal dt As DateTime, ByVal TimeZoneDifference As TimeSpan) As String
    Return New DateTimeOffset(dt.Ticks, TimeZoneDifference).ToString("yyyy-MM-ddTHH:mm:ssZ")
End Function

Public Shared Function GetDatetimewithtimezone(ByVal Timezone As String) As DateTime
    Return (TimeZoneInfo.ConvertTimeFromUtc(DateTime.UtcNow, TimeZoneInfo.FindSystemTimeZoneById(Timezone)))
End Function

Public Shared Function GetTimeSpanDifference(ByVal Timezone As String) As TimeSpan
    Dim timeZoneInfo As TimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById(Timezone)
    Return timeZoneInfo.BaseUtcOffset
End Function

Screenshot