---

async function getContentType(siteUrl, listTitle, itemId) {
  const response = await fetch(
    `${siteUrl}/_api/web/lists/getbytitle('${listTitle}')/items(${itemId})?$expand=ContentType`,
    {
      headers: {
        Accept: "application/json;odata=nometadata"
      }
    }
  );

  const data = await response.json();
  return data.ContentType.Name;
}

(async () => {
  const contentType = await getContentType(siteUrl, listTitle, itemId);
  console.log(contentType);
})();