Timezone offset is not same in server side and client side

Question

I am working on a web application where date time store in database in UTC. Now when I retrieve the date time to show in UI then I have to convert the date time to the specific time from where the user in using the application.

To convert the time from UTC to specific local time I was doing some demo research. I found two way to convert the time. One is from server side and another is from client side. In server side I am using ASP.NET and in client side I am using JavaScript. But the problem is that the answers are not same.

I am giving the code.

Server side:

Label1.Text = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now).ToString();

Client side:

$(document).ready(function () {
    var offset = new Date().getTimezoneOffset();
    $('#Label1').text(offset / 60);
});

In the case of server side code it is showing 05:30:00 in the label. In the case of client side code it is showing -5.5 in the label.

My question is why this two UTC offset is not same ??

Answer 1

The offsets are formatted differently.
The server-side sample appears to be a Date -like object. The client-side version appears to be a int ( 330 ).

The values in these appear to match, though.

Looking at the specification , your server-side code returns a TimeSpan object, while your JavaScript does indeed return a integer.

Answer 2

It's simply a formatting thing. If your offset is +5:30 then getTimezoneOffset will return 330, which is the minutes to add to your local time to get UTC.

If you are passing the time as a value of milliseconds since 1970-01-01T00:00:00Z then you can give that directly to the Date constructor:

var localDate = new Date(timevalue);

To return an equivalent UTC time value, use getTime :

var UTCTimeValue = localDate.getTime();

Javascript date objects use a UTC time value with the system timezone offset to return local date and time values (eg for getDate , getHours , etc.), or UTC values if UTC methods are called (such as getUTCDate , getUTCHours , etc.).