find all hidden element

findhidden.js

function findAllHidden() {
  const all = document.getElementsByTagName('*');
  const hidden = [];
  for (let i = 0; i < all.length; i++) {
    if (window.getComputedStyle(all[i]).display === 'none') {
      hidden.push(all[i]);
    }
  }

  return hidden;
}