time difference

[zuzupus]

hi,

i created a table on which i am showing one clock and in same field user can select time.another field will show time diff


code:--------------------------------------------------------------------------------
<form name=test>
<td>
<select name="from" size="1" onChange="calculateIst()">
<option selected value="08:00">08:00</option>
<option selected value="08:00">08:30</option>
<option selected value="08:00">09:00</option>
<option selected value="08:00">09:30</option>
</select>
</td
<td nowrap>
for clock
//http://www.javascriptkit.com/script/cut2.shtml//
<input type="text" class="button" size="1" name="clock">
<select name="to" size="1" onChange="calculateIst()">
<option selected value="08:00">08:00</option>
<option selected value="08:00">08:30</option>
<option selected value="08:00">09:00</option>
<option selected value="08:00">09:30</option>
</select>
</td>
<td><input size="1" type="text" value="0" name="diff" readonly></td>
</form>
<script>
//timedifference
function calculateIst()
{
var timeFrom = new Date();
var timeTo = new Date();
var timeclock = new Date();
var timediff = new Date();
var time =document.forms["test"].elements["from"].value.split(":");
timeFrom.setHours(time[0]);
timeFrom.setMinutes(time[1]);
var time =document.forms["test"].elements["to"].value.split(":");
timeTo.setHours(time[0]);
timeTo.setMinutes(time[1]);
timediff.setTime(timeTo.getTime() - timeFrom.getTime());
document.forms["test"].elements["diff"].value =timeTo.getHours()-1 + ":" + timeTo.getMinutes();
}
</script>

now problem is when user selects time for TO field then its working cool i mean to say showing time diff between From and To,but when user dont select anything from TO field,the value of running clock(clock field) should be displayed in diff. field (between From and clock)automatically is it possible

in this script another problem i am trying to retrieve the value of clock and To which is in same field for To field its working fine
<input size="1" type="text" name="to" readonly></td>
its not working for clock(how to get value of clock when user clicks on submit button on below field,the problem is its always giving To field value on this clock field)
<input size="1" type="text" name="clock" readonly></td>