How to convert hh:mm:ss string to time and add 30 minutes to it?

How to convert hh:mm:ss string to time and add 30 minutes to it?

Hi
I have Time string like so 15:00:00 which is 3 PM. Now I want to convert that to a number so i can add minutes to it and then convert it back to the hh:mm:ss format

so I want to create a loop starts at 00:00:00 and go up to 15:30:00
then display the value. 

I have done this is PHP but i need to do it in jQuery

$time = strtotime("00:00:00");

for($i = 0;$i < 48;$i++) {
$time = strtotime("+ 30 minutes",$time);
$key = date("H:i:s",$time);
$display = date("g:i A",$time);
$menu .= $display. '<br />';
}