function that returns used elements in a document

getElements.js

function getElements({ sort = true } = {}) {
  let elems = Array.from(document.getElementsByTagName("*")).map(
    (e) => e.localName
  );

  let map = new Map();

  for (let elem of elems) {
    if (!map.has(elem)) {
      map.set(elem, 1);
      continue;
    }
    map.set(elem, map.get(elem) + 1);
  }

  elems = Array.from(map);

  if (sort) {
    elems.sort((a, b) => b[1] - a[1]);
  }

  return elems;
}