Add Tracking Code With Dynamic Variable

add-tracking-code.php

<?php

/**
 * Random Tracking Code
 */

/**
 * Adds Tracking script to footer of thank-you page
 */
function coa_add_trackingCode($order_id) {
	$order = wc_get_order($order_id);
	$order_number = $order->get_order_number();
	$trackingCode_store_id = 'XXXXXX';

	echo <<<END
<div class="code-cta" style="width: 500px; margin: 0 auto;">
	<script type="text/javascript">
		var _cnx = _cnx || [];

		_cnx.push(['mid', {$trackingCode_store_id}]);
		_cnx.push(['surveyType', 'pos']);
		_cnx.push(['orderId', '{$order_number}']);

		(function (w, d, t) {
			var s = d.createElement(t);
			s.async = true;
			s.src = '//example.com/js/init.js';
			var h = d.getElementsByTagName(t)[0]; h.parentNode.insertBefore(s, h);
		})(window, document, 'script');
	</script>
</div>
END;
}

add_action('woocommerce_thankyou', 'coa_add_trackingCode');