After the form submit to get the form data value in aftersubmit() function under the additional tab

<script>
function afterSubmit(form){
var s = $(form).serialize();
var searchParams = new URLSearchParams(decodeURIComponent(s));
var x = decodeURIComponent(s);
var url_string = "https://cs-ecs.myshopify.com?"+x;
var url = new URL(url_string);
var c = url.searchParams.get("website");
console.log(c);
return true;
}
</script>


Like below screenshot:

NOTE: This option only for the advance plan of the app.