Where to add Shopback integration and transaction ID on the homepage?

Shopify Discussion
,
1

With the integration of Shopback, it requires to add this on the home page.

$(document).ready(function(){

var url_string = window.location.href;
var url = new URL(url_string);
var source = url.searchParams.get("utm_source");
var transaction = url.searchParams.get("utm_content");
if(source == "shopback"){
localStorage.setItem('utm_source', source);
localStorage.setItem('transaction_id', transaction);
}
})

Do you guys have any ideas on where to add this? This would require the transaction_id also.