Increment time in form

[Targa]

I have a form field which displays a time in the format 5:30 PM - this time
is selected from a previous page.
I need to add a function to increment or deincrement the time by clicking
up/down buttons - sort of like the clock in Windows.

How can this be done in javascript?

Thanks in advance!

 

[Vincent van Beveren]

// disassambles to values
function processToValues() {
value = document.myform.time.value;
column = value.indexOf(":");
space = value.indexOf(" ");
half = value.substring(space+1);

// half would now countain PM or AM
hours = value.substring(0, column);
minutes = value.substring(column+1,space);
}

function increment() {
minutes++;
if (minutes>59) {
minutes=0;
hours++;
if (hours==12) {
// am->pm->am
// for now, case sensetive
half = (half=='PM'?'AM':'PM');
}
if (hours>12) {
hours = 1;
}
}
}

You should be able to figure out the rest. Good luck,
Vincent