How can I include a code snippet in header of certain pages?

Question

In OpenCart, the section is generated via header.tpl

How can I include a code snippet (such as Facebook conversion tracking code) only in the checkout/success page's header?

Answer 1

Replace common/home in the next example with the correct route:

if ((isset($this->request->get['route']) && $this->request->get['route'] == 'common/home')) { 
    $this->document->addScript('javascript/facebook_tracking_code.js');
}

Or do it inline (in a template):

<?php if ((isset($this->request->get['route']) && $this->request->get['route'] == 'common/home')) { ?>
<script src="javascript/facebook_tracking_code.js"></script>
<?php } ?>