Client TimeZone

  • Thread starter Thread starter Allen Davis
  • Start date Start date
A

Allen Davis

Is there no way in ASP.NET to retrieve the client's timezone (or even local
time, I'd settle for that) and passing it to the server? There must be a way
of determining the timezone from which the web browser is coming from...
mustn't there?
 
Javescript: Date.getTimezoneOffset()

You pass this value to a hidden field. Upon postback, you can read the
value.
 
Hi Allen,


Thank you for using Microsoft newsgroup Service. Based on your description,
you want to get the UTC offset of the client side in ASP.NET serverside or
just transfer such info to serverside? Is my understanding correct?

As for this question, I think you Guogang's suggestion is quite good.
Though in dotnet framework, there isn't direct interface for you to get the
client side's UTC offset, you can do it pretty easily via some clientside
script. Just as the Gogang said that use the javascript's code
"Date.getTimezoneOffset()" and transfer the result to serverside by a
hidden input area. For example
use such page elements:

<td>
<input type="button" value="getclientutc" onclick="GetClientUTC()">
<input type="hidden" id="hdClientUTC" runat="server">
</td>

then add the javascript function:
<script language="javascript">

function GetClientUTC()
{
var now = new Date()
var offset = now.getTimezoneOffset();
document.Form1.hdClientUTC.value = offset
}
</script>

Please try out the suggestion. If you have any questions, please feel free
to let me know.



Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)
 
Steven,

Thanks for the function. It works just fine. I've placed it in the <HEAD>
section of my ASPX page and can successfully pass the value of the hidden
variable to the server if I use the button. But I'm Java clueless so bear
with me and answer another question if you're willing, please.

How can I execute that JavaScript function when the page loads so the
variable is immediately available to my server-side code? I tried a few
things including the <body onload> method but haven't had much luck.
 
Hi Allen,


Thanks for your response. I'm very glad that my suggestion has helped you.
As for the problem you mentioned in the reply, my understanding is:
You want to get the client's UTC offset information at the serverside in
the first time the page is loaded( in the Page_Load event)? Please feel
free to correct me if I misunderstand your problem.


As for the <body onload=".." ..> event you set in the page, it is a
clientside event which will be fired when the page is requested and
returned back to the clientside's browser. And that is after the first time
the page is loaded on the serverside(Page_Load event). So when the page is
first time loaded on the serverside(first time Page_Load is fired), no
client offset info is avaliable. Only after the page is post back to
serverside again(this time the client utc offset info has been set into
those hidden fields via the clientside javascript).

If you think it is necessary to get this information in advance on the
serverside. I've a suggestion that you try check the Page_Load event, if it
is first called(not PostBack), then you set a period of client script using
the Page.RegisterStartupScript" to let the page be posted back right after
get the client utc offset info. How do you think of this?

Please check the above suggestion. If you have anything unclear on them,
please feel free to let me know.



Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)
 
Steven

Another very good suggestion for the JavaScript neophyte. So here's what I did. In my code-behind page (I haven't added the comment tags to the javascript yet, they were tripping me up)..

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Loa
Dim scriptGetClientUTCOffset As String = "<script language=javascript>
scriptGetClientUTCOffset &= "var now = new Date();
scriptGetClientUTCOffset &= "var offset = now.getTimezoneOffset();
scriptGetClientUTCOffset &= "document.Form1.hidClientUTCOffset.value = offset;
scriptGetClientUTCOffset &= "document.Form1.submit()
scriptGetClientUTCOffset &= "</script>

If Not Page.IsPostBack The
If (Not Me.IsStartupScriptRegistered("Startup")) The
Me.RegisterStartupScript("Startup", scriptGetClientUTCOffset
End I
Calendar.SelectedDate = Toda
End I
Label1.Text = hidClientUTCOffset.Valu
DataList1.DataBind(
End Su

I use that together with <input type="hidden" id="hidClientUTCOffset" runat="server"> in my ASPX page and, as soon as the page is opened, Label1's text is set to the client's UTC offset in minutes (I'm assuming as an integer)

So this has certainly solved my dilemna... now if I can just figure out how to take that value and use it in conjunction with the TimeZone object to produce some effective results. Something besides a little 300 or 360 in the upper-left corner of my page. :

Thanks again for your direction on this

----- Steven Cheng[MSFT] wrote: ----

Hi Allen


Thanks for your response. I'm very glad that my suggestion has helped you.
As for the problem you mentioned in the reply, my understanding is
You want to get the client's UTC offset information at the serverside in
the first time the page is loaded( in the Page_Load event)? Please feel
free to correct me if I misunderstand your problem


As for the <body onload=".." ..> event you set in the page, it is a
clientside event which will be fired when the page is requested and
returned back to the clientside's browser. And that is after the first time
the page is loaded on the serverside(Page_Load event). So when the page is
first time loaded on the serverside(first time Page_Load is fired), no
client offset info is avaliable. Only after the page is post back to
serverside again(this time the client utc offset info has been set into
those hidden fields via the clientside javascript).

If you think it is necessary to get this information in advance on the
serverside. I've a suggestion that you try check the Page_Load event, if it
is first called(not PostBack), then you set a period of client script using
the Page.RegisterStartupScript" to let the page be posted back right after
get the client utc offset info. How do you think of this

Please check the above suggestion. If you have anything unclear on them,
please feel free to let me know



Steven Chen
Microsoft Online Suppor

Get Secure! www.microsoft.com/securit
(This posting is provided "AS IS", with no warranties, and confers no
rights.
 
Hi Allen,

Thanks for your response. I'm very glad that we've resolved this issue.
Have a good day!


Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)
 
As a follow up to my last post, here's the function I use to turn that client offset integer into something useful.

Function LocalTime(ByVal dtm As DateTime)
Dim dtmDBUTC As DateTime = dtm.ToUniversalTime
Dim dtmClient As DateTime = dtmDBUTC.AddMinutes(-hidClientUTCOffset.Value)
Return dtmClient
End Function

I still have no leads on how to correctly reflect the English standard name for the client's time zone though. That seems to be a much more difficult challenge.
 
Hi Allen,


Thanks for your followup. As for the problem how to using the Timezone, I
think you can make full use of the javascript functions to do much more
operations onclient side so as not to put all the calculations on the
serverside. The javascript object "Date" has many useful functions, for
example:
---------------------------------------------------
Methods Explanation NN IE ECMA
Date() Returns a Date object 2.0 3.0 1.0
getDate() Returns the date of a Date object (from 1-31) 2.0 3.0 1.0
getDay() Returns the day of a Date object (from 0-6. 0=Sunday, 1=Monday,
etc.) 2.0 3.0 1.0
getMonth() Returns the month of a Date object (from 0-11. 0=January,
1=February, etc.) 2.0 3.0 1.0
getFullYear() Returns the year of a Date object (four digits) 4.0 4.0 1.0
getYear() Returns the year of a Date object (from 0-99). Use getFullYear
instead !! 2.0 3.0 1.0
getHours() Returns the hour of a Date object (from 0-23) 2.0 3.0 1.0
getMinutes() Returns the minute of a Date object (from 0-59) 2.0 3.0 1.0
getSeconds() Returns the second of a Date object (from 0-59) 2.0 3.0 1.0
getMilliseconds() Returns the millisecond of a Date object (from 0-999) 4.0
4.0 1.0
getTime() Returns the number of milliseconds since midnight 1/1-1970 2.0
3.0 1.0
getTimezoneOffset() Returns the time difference between the user's computer
and GMT 2.0 3.0 1.0
getUTCDate() Returns the date of a Date object in universal (UTC) time 4.0
4.0 1.0
getUTCDay() Returns the day of a Date object in universal time 4.0 4.0 1.0
getUTCMonth() Returns the month of a Date object in universal time 4.0 4.0
1.0
getUTCFullYear() Returns the four-digit year of a Date object in universal
time 4.0 4.0 1.0
getUTCHours() Returns the hour of a Date object in universal time 4.0 4.0
1.0
getUTCMinutes() Returns the minutes of a Date object in universal time 4.0
4.0 1.0
getUTCSeconds() Returns the seconds of a Date object in universal time 4.0
4.0 1.0
getUTCMilliseconds() Returns the milliseconds of a Date object in universal
time 4.0 4.0 1.0
parse() Returns a string date value that holds the number of milliseconds
since January 01 1970 00:00:00 2.0 3.0 1.0
setDate() Sets the date of the month in the Date object (from 1-31) 2.0 3.0
1.0
setFullYear() Sets the year in the Date object (four digits) 4.0 4.0 1.0
setHours() Sets the hour in the Date object (from 0-23) 2.0 3.0 1.0
setMilliseconds() Sets the millisecond in the Date object (from 0-999) 4.0
4.0 1.0
setMinutes() Set the minute in the Date object (from 0-59) 2.0 3.0 1.0
setMonth() Sets the month in the Date object (from 0-11. 0=January,
1=February) 2.0 3.0 1.0
setSeconds() Sets the second in the Date object (from 0-59) 2.0 3.0 1.0
setTime() Sets the milliseconds after 1/1-1970 2.0 3.0 1.0
setYear() Sets the year in the Date object (00-99) 2.0 3.0 1.0
setUTCDate() Sets the date in the Date object, in universal time (from
1-31) 4.0 4.0 1.0
setUTCDay() Sets the day in the Date object, in universal time (from 0-6.
Sunday=0, Monday=1, etc.) 4.0 4.0 1.0
setUTCMonth() Sets the month in the Date object, in universal time (from
0-11. 0=January, 1=February) 4.0 4.0 1.0
setUTCFullYear() Sets the year in the Date object, in universal time (four
digits) 4.0 4.0 1.0
setUTCHour() Sets the hour in the Date object, in universal time (from
0-23) 4.0 4.0 1.0
setUTCMinutes() Sets the minutes in the Date object, in universal time
(from 0-59) 4.0 4.0 1.0
setUTCSeconds() Sets the seconds in the Date object, in universal time
(from 0-59) 4.0 4.0 1.0
setUTCMilliseconds() Sets the milliseconds in the Date object, in universal
time (from 0-999) 4.0 4.0 1.0
toGMTString() Converts the Date object to a string, set to GMT time zone
2.0 3.0 1.0
toLocaleString() Converts the Date object to a string, set to the current
time zone 2.0 3.0 1.0
toString() Converts the Date object to a string 2.0 4.0 1.0
----------------------------------------------------------------------------
-------------------

For more detailed info on this javascript class, you may view the following
reference:
http://www.w3schools.com/js/js_datetime.asp

In addition, here is some tech articles on how to deal with the UTC
time(both clienside or serverside)
#Javascript Date and Time 5 : Date and Time Elsewhere
http://www.merlyn.demon.co.uk/js-date5.htm

#Date/Time display in local time
http://www.dotnet247.com/247reference/msgs/22/110400.aspx

Hope they are helpful.


Regards,

Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)
 
Hi Allen,

As for the problem "get the Timezone via a specified offset value", I've
done some further researchs and asked some other specialists for infos. It
seems that via Win32 and .Net, the only way to get a Timezone name, given
only an offset, would be to create a lookup table. So do you think it
proper to use a manually created lookup table to workaround this prolbem?

Please feel free to post here if you have any further questions.


Regards,

Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)
 
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