Get Client-Size TimeZone offset to Serverside to get local times of dates stored as utc for MVC app


I am trying to display a table showing meeting dates that I have saved as UTC in the local time.  I think I know how to get the local timezone offset ??
 var d = new Date()
            var javaScriptTimeZoneOffset = d.getTimezoneOffset();

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However I can't figure out how to use that server-side to generate the ViewModel that I need to display the time-zone adjusted dates.  My code looks like this:

public ActionResult AvailableMeetings()
            //var utcOffset = ?? - get from javaScriptTimeZoneOffset 

            var meetings = _context.Meetings
                .Select(meeting => new TimeZoneAdjustedViewModel
                    Id = meeting.Id,
                    Start = DateTime.SpecifyKind(meeting.Start, DateTimeKind.Utc).AddMinutes(utcOffset),

            return View(meetings);

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Any help in accomplishing this would be greatly appreciated.

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I would suggest that you keep the server blissfully unaware of client's timezones. Keep the dates in UTC and for any conversions/input/presentation use a javascript date library like
RBSAuthor Commented:
Thank you - but that does not answer my question.  I need to get the offset to store in a session variable or whatever so that I can present the available times in the user's local time zone.
Bob LearnedCommented:
If you have a UTC time, then you should be able to use the DateTime.ToLocalTime method to convert to local time, depending on the current locale.
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RBSAuthor Commented:
Hi Bob:

Thank you.  DateTime.ToLocal Time returns the utc offset based on where the server is located.  I need to get the utcOffset based on where the client machine is - i.e. the time zone set in the user's computer clock - that's why I'm using javascript.

greetings RBS, , there are essentially two ways that I know to do this, , You can use the getTimezoneOffset( ) to get the Minutes from GMT to JS local time-
    var d = new Date()
    var offMinutes = d.getTimezoneOffset();

and then change the minutes (milliseconds) in the server date.

OR, it may be possible to use -
    var dt = new Date(Date.UTC(2015,06,22,10,45));

depending on how you get the server UTC (GMT) JS time variable.

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Here's one potential approach:
var tzoMinutes = - (new Date).getTimezoneOffset();
document.cookie = "tzoMin=" + tzoMinutes;

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The first line is basically what Slick812 suggested.

The second line stashes the result in a browser cookie.  On successive page-requests made by that browser, the server can grab that value from the request's cookies.  For example:
string tzoMin = Request.Cookies["tzoMin"]; // or equivalent, depending on exactly where this code is (page, controller, view, etc.)
int utcOffset = 0;
if(!string.isNullOrEmpty(tzoMin)) {
    int.TryParse(tzoMin, out utcOffset);

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Hope that helps.
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