How to get client date and time in ASP.NET?

Question

When I use DateTime.Now I get the date and time from the server point of view. Is there any way to get the client date and time in ASP.NET?

Answer 1

I like the idea of either using the browser/system time and time zone or letting them select their time zone. In a past project I used something like this:

<script language="javascript">
function checkClientTimeZone()
{
    // Set the client time zone
    var dt = new Date();
    SetCookieCrumb("ClientDateTime", dt.toString());

    var tz = -dt.getTimezoneOffset();
    SetCookieCrumb("ClientTimeZone", tz.toString());

    // Expire in one year
    dt.setYear(dt.getYear() + 1);
    SetCookieCrumb("expires", dt.toUTCString());
}

// Attach to the document onload event
checkClientTimeZone();
</script>

And then on the server:

/// <summary>
/// Returns the client (if available in cookie) or server timezone.
/// </summary>
public static int GetTimeZoneOffset(HttpRequest Request)
{
    // Default to the server time zone
    TimeZone tz = TimeZone.CurrentTimeZone;
    TimeSpan ts = tz.GetUtcOffset(DateTime.Now);
    int result = (int) ts.TotalMinutes;
    // Then check for client time zone (minutes) in a cookie
    HttpCookie cookie = Request.Cookies["ClientTimeZone"];
    if (cookie != null)
    {
        int clientTimeZone;
        if (Int32.TryParse(cookie.Value, out clientTimeZone))
            result = clientTimeZone;
    }
    return result;
}

Or you can pass it in as a URL parameter and handle it in the Page_Load:

http://host/page.aspx?tz=-360

Just remember to use minutes, since not all time zones are whole hours.