Fetch and parse XML in windows-1251 encoding from vk.com - getting basic user information

foaf.js

/**
 * Quick experiment
 * retrieve users data as XML from VK "secret" /foaf.php endpoint
 * and extract some values, using 2022 browser APIs.
 *
 * This can be run in browser console, when any page on vk.com is open
 * otherwise a cross-domain request is disallowed.
 *
 * By Sergei Sokolov,
 * Moscow, Russia, November 2022.
 */

/**
 * Given integer VK user ID, returns an XMLDocument with users data
 *
 * @param {number} id
 * @returns {XMLDocument}
 */
const getXMLDocument = async id => {
  try {
    const response = await fetch(`https://vk.com/foaf.php?id=${id}`);
    const buffer = await response.arrayBuffer();
    const decoder = new TextDecoder("windows-1251");
    const rawXML = decoder.decode(buffer);
    const xml = rawXML.replace(/&(?!amp;)/g, '&'); // fix VK image URLs
    const parser = new DOMParser();
    const doc = parser.parseFromString(xml, 'text/xml');
    return doc;
  } catch (error) {
    console.error("Caught error:", error);
  }
}

/**
 * Find some nodes and extract their data
 * @param {XMLDocument} xmlDocument
 * @returns {Object} data
 */
const extractData = xmlDocument => {
  const getDate = tagName => xmlDocument.getElementsByTagName(tagName)[0].getAttribute('dc:date');
  const getText = tagName => xmlDocument.getElementsByTagName(tagName)[0].textContent;

  const lastLoggedIn = getDate('ya:lastLoggedIn');
  const created = getDate('ya:created');
  const firstName = getText('ya:firstName');
  const secondName = getText('ya:secondName');
  const gender = getText('foaf:gender');

  return { lastLoggedIn, created, firstName, secondName, gender };
}

/**
 * Workflow run
 * @param {number} id - VK user ID
 */
const foaf = async id => {
  const doc = await getXMLDocument(id);
  if (!doc) return;
  console.log(extractData(doc));
};

foaf(1); // 1 is Pavel Durov's VK id