Find font usage on a page and what elements use it

fontElementMap.js

function fontElementMap(selector = "*", onlyVisible = true) {
  const allElements = document.querySelectorAll(selector);
  const fontElements = {};

  for (element of allElements) {
    const style = window.getComputedStyle(element);
    const fontFamily = style.getPropertyValue("font-family");

    if (!fontFamily) {
      continue;
    }

    if (onlyVisible && style.getPropertyValue("display") === "none") {
      continue;
    }

    fontElements[fontFamily] = fontElements[fontFamily] || [];
    fontElements[fontFamily].push(element);
  }

  return fontElements;
}