If you want to do the job properly, you should do this all on server side and for that please refer to this answer:
How do you parse and process HTML/XML in PHP?
Otherwise this should solve your problem in a quicker way:
<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="content-type">
<script src="//code.jquery.com/jquery-1.11.0.js" type="text/javascript"></script>
<script type="text/javascript">
$(window).load(function(){
var strikePrice = new Array();
$(".opttbldata").find("tr").each( function (row, currentTR) {
if (row > 1) { // Avoid first two header rows (0 based index)
var columnContent = $(currentTR).find("td:eq( 6 )").text();
strikePrice[row-2] = (columnContent=="-"?" 0":columnContent); // Strike price column (0 based index)
}
});
$("#NSEIndiaData").remove(); // Get rid of the loaded page/data to uncluter the DOM
alert(strikePrice);
});
</script>
</head>
<body>
<?php
$curlSession = curl_init();
curl_setopt($curlSession, CURLOPT_URL, 'http://www.nseindia.com/live_market/dynaContent/live_watch/option_chain/optionKeys.jsp?symbolCode=-10007&symbol=NIFTY&symbol=NIFTY&instrument=OPTIDX&date=-&segmentLink=17&segmentLink=17');
curl_setopt($curlSession,CURLOPT_USERAGENT,'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13');
curl_setopt($curlSession, CURLOPT_BINARYTRANSFER, true);
curl_setopt($curlSession, CURLOPT_RETURNTRANSFER, true);
$homepage = curl_exec($curlSession);
?>
<div id="NSEIndiaData" style="display: none;">
<?php var_dump($homepage); ?>
</div>
<?php
curl_close($curlSession);
?>
</body>
</html>
All values of column 12 will be placed inside a 0 index based Array which you can later manipulate at will.