This is my code added to the Pardot form below section,

// Parse the URL

function getParameterByName(name) {
name = name.replace(/[[]/, "\[").replace(/[]]/, "\]");
var regex = new RegExp("[\?&]" + name + "=([^&#]*)"),
results = regex.exec(location.search);
return results === null ? "" : decodeURIComponent(results[1].replace(/+/g, " "));
}

// Give the URL parameters variable names

var source = getParameterByName('utm_source');
var medium = getParameterByName('utm_medium');
var campaign = getParameterByName('utm_campaign');
var content = getParameterByName('utm_content');
var term = getParameterByName('utm_term');
var campaignID = getParameterByName('URL_Campaign_Id');

// GET the URL of the Parent Page

var url = window.location.href;

// Put the variable names into the hidden fields in the form. selector should be "p.YOURFIELDNAME input"

document.querySelector("p.utm_source input").value = source;
document.querySelector("p.utm_medium input").value = medium;
document.querySelector("p.utm_campaign input").value = campaign;
document.querySelector("p.utm_content input").value = content;
document.querySelector("p.utm_term input").value = term;
document.querySelector("p.URL_Campaign_Id input").value = campaignID;
document.querySelector('input[name="Source_URL"]').value = url;

I want to fetch the URL of the form and store it in the hidden field(Source_URL) when someone submits the Pardot form the whole code works fine but just the part of fetching the URL and storing to "Source_URL" hidden field is not working.

Does anyone have a solution what change do I have to make here?

Adding image of code also to clearly understand the code