JavaScript clock that takes daylight savings time into account

[Katie6]

Hi there,

I'm using the following script which allows users to choose the time zone of a javascript clock.

Choose time zone:
<form name="where">
<select name="city" size="1" onchange="updateclock(this);"> 
<option value="" selected>Local time</option>
<option value="0">London GMT</option> 
<option value="1">Rome</option>
<option value="7">Bangkok</option>
<option value="8">Hong Kong</option>
<option value="9">Tokyo</option> 
<option value="10">Sydney</option>
<option value="12">Fiji</option>
<option value="-10">Hawaii</option>
<option value="-8">San Francisco</option> 
<option value="-5">New York</option>
<option value="-3">Buenos Aires</option>
</select>
<script type="text/javascript">
/*
Drop Down World Clock- By JavaScript Kit ([URL unfurl="true"]http://www.javascriptkit.com)[/URL]
Portions of code by Kurt @ [URL unfurl="true"]http://www.btinternet.com/~kurt.grigg/javascript[/URL]
This credit notice must stay intact
*/

if (document.all||document.getElementById)
document.write('<span id="worldclock"></span><br />')

zone=0;
isitlocal=true;
ampm='';

function updateclock(z){
zone=z.options[z.selectedIndex].value;
isitlocal=(z.options[0].selected)?true:false;
}

function WorldClock(){
now=new Date();
ofst=now.getTimezoneOffset()/60;
secs=now.getSeconds();
sec=-1.57+Math.PI*secs/30;
mins=now.getMinutes();
min=-1.57+Math.PI*mins/30;
hr=(isitlocal)?now.getHours():(now.getHours() + parseInt(ofst)) + parseInt(zone);
hrs=-1.575+Math.PI*hr/6+Math.PI*parseInt(now.getMinutes())/360;
if (hr < 0) hr+=24;
if (hr > 23) hr-=24;
ampm = (hr > 11)?"PM":"AM";
statusampm = ampm.toLowerCase();

hr2 = hr;
if (hr2 == 0) hr2=12;
(hr2 < 13)?hr2:hr2 %= 12;
if (hr2<10) hr2="0"+hr2

var finaltime=hr2+':'+((mins < 10)?"0"+mins:mins)+':'+((secs < 10)?"0"+secs:secs)+' '+statusampm;

if (document.all)
worldclock.innerHTML=finaltime
else if (document.getElementById)
document.getElementById("worldclock").innerHTML=finaltime
else if (document.layers){
document.worldclockns.document.worldclockns2.document.write(finaltime)
document.worldclockns.document.worldclockns2.document.close()
}


setTimeout('WorldClock()',1000);
}

window.onload=WorldClock
//-->

</script>

<!--Place holder for NS4 only-->
<ilayer id="worldclockns" width=100% height=35><layer id="worldclockns2" width=100% height=35 left=0 top=0 style="font:bold 16px Arial;"></layer></ilayer>
</form>

I'd like to add something which will enable me to take daylight savings time (DST) into account. Some countries e.g. UK have DST, but other countries e.g. Hong Kong do not. I would like to be able to set a flag for each of the countries (e.g. id="0" or id="1") to set whether the country has DST or not. I would like this flag to be used to make the time automatically change on the correct date if the flag is equal to 1.

If anyone could help, that'd be great.

Many thanks,

Katie.

 

[BabyJeffy]

Katie,

You should contact the original author of the script if you need modifications made (this is not the place for that kind of request). If you are attempting to do this yourself, then let us know what you have tried and what problems you are experiencing.

Personally, given that the rules for DST change (the US and NZ changed the date that DST started this year I think) it could be problematic to implement client-side (where do you get the rules from, for instance).

Cheers,
Jeff

[tt]Jeff's Blog [!]@[/!] CodeRambler

http://www.coderambler.com/

http://www.coedit.co.uk/

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Make sure your web page and css validates properly against the doctype you have chosen - before you attempt to debug a problem!

FAQ216-6094