pardot-hidden-fields.js

// Get the name of the Parsely visitor cookie
const parselyVisitorCookieName = window.PARSELY.visitorManager.visitorCookieName || '_parsely_visitor';

// Get the visitor object from the Parsely cookie
const parselyVisitor = window.PARSELY.ParselyStorage.getJSON(parselyVisitorCookieName);

// Construct hidden fields to pass to the Pardot iframe
// The `parentUrl` will be the URL in which the iframe is embedded
// The `conversionType` and `conversionLabel` should be set per the Parsely docs: https://www.parse.ly/help/integration/conversions-self-managed-integration#conversion-types
const hiddenFieldsObject = {
  parsely_conversion_label: conversionLabel,
  parsely_conversion_type: conversionType || 'lead_capture',
  parsely_visitor_id: parselyVisitor.id,
  parsely_visitor_last_session_ts: parselyVisitor.last_session_ts,
  parsely_visitor_session_count: parselyVisitor.session_count,
  parent_url: parentUrl,
};

// Encode the hidden fields as URL query params
const hiddenFields = Object.entries(hiddenFieldsObject)
  .map(([key, value]) => `${key}=${value}`)
  .join('&');

// Pass the `hiddenFields` appended to the `formUrl` for the iframe
// Note: Here we are using JSX, but the idea would be the same for HTML
<iframe
  src={`${formUrl}?${hiddenFields}`}
  width="100%"
  type="text/html"
  frameBorder="0"
/>