Simple JS time manipulation

JavaScript
1

I want a script to receive a time in the 24 hour time format HH:mm (e.g. 18:30) and remove 15 minutes from it.

The problem is that if the time inputted was 00:00, then how do I get to 23:45?

I’m sure it’s easy if you’re in the know.

I can do this with PHP, but not with JS.

I just need the function / basic line of code that does this. I can work out how to call it etc. myself.

Thanks for any help.

John

2 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">

<head>
  <title></title>
</head>

<body>

<script type="text/javascript">
/*<![CDATA[*/

function Time(time,less){
  var time=time.split(':'),date=new Date(2011,6,1,time[0]*1,time[1]*1+less),hrs=date.getHours(),min=date.getMinutes();
  return (hrs>9?hrs:'0'+hrs)+':'+(min>9?min:'0'+min);
}

alert(Time('4:24',-15));
alert(Time('00:00',-15));
/*]]>*/
</script>
</body>

</html>
3

Perfect. Thanks Vic.