Getting Variable From Script To HTML Form

Here is some code (I did not write) which counts down the minutes allowed on an exam. I want to get the minutes remaining when the user submits the exam and store this in a mysql database. My question is what is the variable which communicates the remaining time? And how do I put it in a form so I can pass it once the user submits?

<script language="JavaScript" type="text/javascript">
k = new Date();
n= k.getMinutes();
k.setMinutes(n+<? echo $minutes; ?>);
TargetDate = k;
BackColor = "palegreen";
ForeColor = "navy";
CountActive = true;
CountStepper = -1;
LeadingZero = true; .....