Google Analytics Plugin - trigger on the last page

$js = '
<!-- Google Analytics ecommerce -->
<script>
(function(i,s,o,g,r,a,m){i["GoogleAnalyticsObject"]=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,"script","//www.google-analytics.com/analytics.js","ga");

ga("create", "' . $account . '", "auto");
ga("send", "pageview");'.$extra_required.'
ga("require", "ecommerce", "ecommerce.js");

ga("ecommerce:addTransaction", {
	"id": "' . $order->order_id.'",
	"affiliation": "' . str_replace(array('\\','"'), array('\\\\', '\\\"'), $siteName) . '",
	"revenue": "' . round($order->order_full_price, 2) . '",
	"shipping": "' . round($order->order_shipping_price, 2) . '",
	"tax": "' . round($tax, 2) . '"
});
';

			foreach($order->products as $product) {
				$js .= '
ga("ecommerce:addItem", {
	"id": "' . $order->order_id . '",
	"name": "' . str_replace(array('\\','"'), array('\\\\', '\\\"'), strip_tags($product->order_product_name)) . '",
	"sku": "' . str_replace(array('\\','"'), array('\\\\', '\\\"'), $product->order_product_code) . '",
	"category": "",
	"price": "' . ($product->order_product_price + $product->order_product_tax) . '",
	"quantity": "' . (int)$product->order_product_quantity . '"
});
';
			}

			$js .= '
ga("ecommerce:send");
</script>
<!-- End Google Analytics -->
';

echo $js;

$siteName = 'your site name';

$account= 'your analytics account (UA-)';

$app = JFactory::getApplication();
$order_id = $app->getUserState('com_hikashop.order_id');
$orderClass = hikashop_get('class.order');
$this->order = $orderClass->loadFullOrder($order_id); 

$order_total = round($this->order->order_full_price, 2);
$shipping_price =  round($this->order->order_shipping_price, 2);
$revenue = $order_total - $shipping_price;
$order_total_no_vat = round($this->order->order_subtotal_no_vat, 2);
$tax =  $order_total - $order_total_no_vat;

$js = '
<!-- Google Analytics ecommerce -->
<script>
(function(i,s,o,g,r,a,m){i["GoogleAnalyticsObject"]=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,"script","//www.google-analytics.com/analytics.js","ga");

ga("create", "' . $account . '", "auto");
ga("send", "pageview");'.$extra_required.'
ga("require", "ecommerce", "ecommerce.js");

ga("ecommerce:addTransaction", {
	"id": "' . $order_id .'",
	"affiliation": "' . str_replace(array('\\','"'), array('\\\\', '\\\"'), $siteName) . '",
	"revenue": "' . $revenue . '",
	"shipping": "' . $shipping_price . '",
	"tax": "' . round($tax, 2) . '"
});
';

foreach($this->order->products as $product) {
	$js .= 
	'ga("ecommerce:addItem", {
	"id": "' . $order_id . '",
	"name": "' . str_replace(array('\\','"'), array('\\\\', '\\\"'), strip_tags($product->order_product_name)) . '",
	"sku": "' . str_replace(array('\\','"'), array('\\\\', '\\\"'), $product->order_product_code) . '",
	"category": "",
	"price": "' . ($product->order_product_price + $product->order_product_tax) . '",
	"quantity": "' . (int)$product->order_product_quantity . '"
	});
	';
}

$js .= '
ga("ecommerce:send");
</script>
<!-- End Google Analytics -->
';

echo $js;