getAncestors

Returns all the ancestors of an element from the document root to the given element.

• Use Node.parentNode and a while loop to move up the ancestor tree of the element.
• Use Array.prototype.unshift() to add each new ancestor to the start of the array.

const getAncestors = el => {
  let ancestors = [];
  while (el) {
    ancestors.unshift(el);
    el = el.parentNode;
  }
  return ancestors;
};

getAncestors(document.querySelector('nav')); 
// [document, html, body, header, nav]