document.reduce() - querySelectorAll() but with a callback instead of a selector

document-reduce.js

document.reduce = Element.prototype.reduce = function(cb) {
  const filter = node => cb(node) ? NodeFilter.FILTER_ACCEPT : NodeFilter.FILTER_REJECT;

  // Old IE requires a function other browsers require { acceptNode }.
  filter.acceptNode = filter;

  // Old IE requires the last parameter.
  const walker = document.createTreeWalker(this, NodeFilter.SHOW_ELEMENT, null, false);

  const nodels = [];
  while (walker.nextNode()) {
    const { currentNode } = walker;
    if (cb(currentNode)) {
      nodels.push(currentNode);
    }
  }
  return nodels;
};