// when = e.namedValues["Timestamp"].toString()

const getFormResponseURL = (when) => {
  const formUrl = SpreadsheetApp.getActive().getFormUrl();

  const form = FormApp.openByUrl(formUrl);

  const responseDate = new Date(when);

  // Gets an array of all of the form's responses after a given date and time.

  const responses = form.getResponses(responseDate);

  if (responses.length > 0) {
    return responses[0].getEditResponseUrl();
  }

  return '';
};