What best way to fire the Facebook conversion pixel without actually loading a "confirmation"/"Thank You" page?

As a simulation of real purchase? I tried the code below, but isnt working actually anymore.

javascript:(function(){ var codigo = document.getElementById("ProductJson-product-template"); if(codigo == undefined){ content_id = meta["product"]["id"]; } else { var content_id = JSON.parse(codigo.text)["id"].toString(); } fbq('track', 'Purchase', { content_type: 'product_group', content_ids: '[' + content_id + ']' , value: 99.00, num_items: 1, currency: 'USD', }); console.log("Pixel successful on content ID: " + content_id); })();