function updateField(checkboxNames, fieldName) {
  // Fetch all checkboxes corresponding to a given field
  var checkboxes = document.getElementsByName(checkboxNames);
  var checks = [];
  for (var box of checkboxes) {
    if (box.checked) {
      checks.push(box.value);
    }
  }

  // Update the field value with all checked box values
  const fieldEl = document.getElementById(fieldName);
  fieldEl.value = checks.join();
}