Build a list of the font families and weights on a web page, with the number of elements using them

Check fonts on a page

const nodes = document.body.getElementsByTagName('*');
const styles = {};

for (const node of nodes) {
  const s = getComputedStyle(node);
  if (!styles[s.fontFamily]) {
    styles[s.fontFamily] = {};
  }
  if (!styles[s.fontFamily][s.fontWeight]) {
    styles[s.fontFamily][s.fontWeight] = 1;
  }
  styles[s.fontFamily][s.fontWeight]++
}

let count = 0;
for (const fam in styles) {
  for (const w in styles[fam]) {
    count++;
    console.log(count, fam, w, styles[fam][w]);
  }
}