How do I display the selected value of a select box in javascript

I built a php page which shows a dropdownlist with a list of dates which are pulled from a database on mysql , so I have a select box  called dateSelectBox  and a button proceedButton . Also I  have a variable called training date as
$training ="Customer Service";
and I want to be able to  show a confirmation message (javascript) which will alert the user , to enroll for that training or cancel.

The popup should say :

confirm(""Are you sure you want to enroll for $training  on dateSelectBox?");

How can I do this in my current code?

<script language="JavaScript">
function confirmSubmit()
{
var agree=confirm("Are you sure you wish to enroll for ?");
if (agree)
      return true ;
else
      return false ;
}
</script>

 

<script>
var what = {
  "date": "<? echo $dateSelectBox; ?>";
}

</script>


if ($_POST['proceedButton'] != '') {

$user =& JFactory::getUser();
$user_id = $user->id;

$user_dept = $user->department;

$department =& JFactory::getUser($user_dept);


$user = JFactory::getUser(); 
$training= "Customer Service";
$id = $user->get('id'); 
$name = $user->get('name');
$username = $user->get('username'); 
//$department = $user->get('department');

$vardate = date("Y-m-d H:i:s");



$vartrainingID = $_POST['dateSelectBox'];

/***************************************/

$db = &JFactory::getDBO();

$query = "
INSERT INTO
`jos_jquarks_persontraining`
(

training_id,user_id,employeeNumber,department,name,timeStamp)
VALUES
(

'{$vartrainingID}',

'{$id}',
'{$username}',
'{$user_dept}',
'{$name}',
'{$vardate}'
)";

$db->setQuery($query);

$db->query();

if($db->getErrorNum()) { 
//JError::raiseError( 500, $db->stderr());

mysql_close($db);

header("Location: index.php?option=com_content&view=article&id=28");
exit();

} 

else {

header("Location: index.php?option=com_content&view=article&id=27");
exit();
}

}

?>

<form name="quiz_info" method="post" onSubmit="return validate(this)" action="<?php echo $_SERVER['REQUEST_URI']; ?>">

<?php

echo JText::_('Please select the date:');

$database= &JFactory::getDBO();

$database->setQuery('SELECT training_id,CONCAT(date_format(trainingDate,"
%W, %M %e, %Y"),"-",trainingHour) AS trainingDates FROM training WHERE openSeats > 0 ORDER BY trainingDate ASC ,training_id');

$result = $database->loadObjectList();


echo '<select name="dateSelectBox">';
foreach ($result as $row) {

echo '<option value="'.$row->training_id.'" text="'.$row->trainingDates.'">'.$row->trainingDates.'</option>';
}
echo '</select>';

?>

<input id="proceedButton" name="proceedButton" value="Enroll" type="submit" onClick="return confirmSubmit()" />
</form>

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