z-index-table.js

((document, limit) => {
  const data = Array.from(document.querySelectorAll('*'))
    .map((el) => ({zIndex: Number(getComputedStyle(el).zIndex), element: el }))
    .filter(({ zIndex }) => !isNaN(zIndex))
    .sort((r1, r2) => r2.zIndex - r1.zIndex)
    .slice(0, limit);
  console.table(data);
})(document, 50);