How to get client datetime in ASP.NET C#?

Question

I think the question says it all. If I use DateTime.Now, then I get the date and time from the server point of view. I've heard of JavaScript solution, but I wonder if there is another solution.

thanks

Answer 1

if you're maintaining a user profile, you can ask them to tell you their timezone, and then do the calculations necessary.

Answer 2

The alternative is to geolocate the user based on his/her IP address. Or geolocate if the browser has this capability (coming soon for Firefox). Once you have the user's location you can lookup the timezone.

The javascript solution is probably a good and easy one.

Answer 3

Client and server may not be totally synchronized, so the question is if you want the time on the client computer, or you want the time on the server, but adjusted for time-zone differences. Javascript can get you the time on the client (including timezone). You can also combine the time on the server with the timezone of the client.

You can never get the time with higher precision than the latcency of a request, though.

Answer 4

What I'd do is create a hidden input field and then wire a Javascript routine to the onsubmit event for the form. This routine would populate the hidden field with the time on the client machine.

The hidden field can used with ASP.NET by using the HTML control "HtmlInputHidden" class. You just give you input control a runat="server" attribute like any other server side control.

The server can then read out this time when the form posts back. You could even wrap this up in a server control if you need to do this in a number of places.

Alternatively, you could do this with AJAX but the implementation will depend on which library you use.

Answer 5

The javascript solution is the only way to go, for now.

Answer 6

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)
{
    TimeZone tz = TimeZone.CurrentTimeZone;
    TimeSpan ts = tz.GetUtcOffset(DateTime.Now);
    int result = (int) ts.TotalMinutes;
    HttpCookie cookie = Request.Cookies["ClientTimeZone"];
    if (cookie != null)
        Int32.TryParse(cookie.Value, out result);
    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.

Answer 7

I guess it all depends on why you want to get the client datetime in the first place, what exactly are you trying to do?