Kód:

<select name="select2" size="1" onChange="updateclock(this);">
        <option value="" selected>Budapest</option>
        <option value="0">London GMT</option>
        <option value="1">Róma</option>
        <option value="7">Bangkok</option>
        <option value="8">Hong Kong</option>
        <option value="9">Tokió</option>
        <option value="7">Peking</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 language="JavaScript" type="text/JavaScript">

if (document.all||document.getElementById)
document.write('<br /><span id="worldclock" style="font:bold size="4" Times New Roman;"><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 > 23)?"":"";
statusampm = ampm.toLowerCase();

hr2 = hr;
if (hr2 == 0) hr2=24;
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>