Within your store's FoxyCart administration, go to the “configuration” section and enable the “Add custom header and footer code to your templates” option. Within the text boxes that appear, paste the following code into the “footer” textarea:

{% if context != "cart" or cart_is_fullpage %}
<!-- Facebook Pixel Code -->
{% set fb_pixel_id = "###########" %}
<script>
	!function(f,b,e,v,n,t,s){if(f.fbq)return;n=f.fbq=function(){n.callMethod?
	n.callMethod.apply(n,arguments):n.queue.push(arguments)};if(!f._fbq)f._fbq=n;
	n.push=n;n.loaded=!0;n.version='2.0';n.queue=[];t=b.createElement(e);t.async=!0;
	t.src=v;s=b.getElementsByTagName(e)[0];s.parentNode.insertBefore(t,s)}(window,
	document,'script','https://connect.facebook.net/en_US/fbevents.js');
 
	fbq('init', '{{ fb_pixel_id }}');
	fbq('track', "PageView");
 
	if (typeof fbq != 'undefined') {
		{% if context == "cart" %}
			fbq('track', 'AddToCart');
		{% elseif context == "checkout" %}
			fbq('track', 'InitiateCheckout');
		{% elseif first_receipt_display %}
  			var item_contents = [];
  			for (var i = 0; i < FC.json.items.length; i++) {
  				item_contents.push({"id": FC.json.items[i].code, "quantity": FC.json.items[i].quantity, "item_price": FC.json.items[i].price_each});
  			}
			fbq('track', 'Purchase', {value: '{{ total_order }}', currency: '{{ locale_info.int_curr_symbol|trim }}', contents: item_contents, content_type: 'product'});
		{% endif %}
	}
</script>
<noscript><img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id={{ fb_pixel_id }}&ev=PageView&noscript=1" /></noscript>
<!-- End Facebook Pixel Code -->
{% endif %}

Within the script, edit the first line to set your Facebook pixel ID {% set fb_pixel_id = “###########” %}.

The script will automatically include the Facebook Pixel initialisation code on the full page cart, checkout and receipt, but will rely on you including it on your own website for the Sidecart view. It will also track page views on the full page cart, checkout and receipt, as well as tracking AddToCart, InitiateCheckout and Purchase events.

On your own website, in order to track the AddToCart event for Sidecart, add the following code to the footer of your website (this assumes you've placed the Facebook Pixel initialisation code on your website already too):

<script>
var FC = FC || {};
FC.existingOnLoad_pixel = (typeof FC.onLoad == "function") ? FC.onLoad : function() {};
 
FC.onLoad = function () {
    FC.existingOnLoad_pixel();
    FC.client.on('cart-submit.done', function(params) {
        if (
            typeof fbq != 'undefined'
            && params.hasOwnProperty('data')
            && params.data.hasOwnProperty('name')
            && FC.client.isActionNeeded(params)
            && (!FC.sidecart || (FC.sidecart
                && !FC.sidecart.shouldUseFullpageCart()
                && !FC.sidecart.bypassSidecart(params)
            ))
        ) {
            var item_quantity = (params.data.hasOwnProperty('quantity') ? parseInt(params.data.quantity) : 1);
            var item_price = parseFloat(params.data.price);
            fbq('track', 'AddToCart', { 'content_name': decodeURIComponent(params.data.name), 'value': (item_price * item_quantity), 'currency': FC.json.locale_info.int_curr_symbol.trim(), 'contents':  [{ 'id': params.data.code, 'quantity': item_quantity, 'item_price': item_price }], 'content_type': 'product' });
        }
    });
}
</script>