[Gist Sorter] Adds a button to sort visible Gists by age #UserScript

Gist Sorter.user.js

// ==UserScript==
// @name         Gist Sorter
// @description  Adds a button to sort visible Gists by age
// @version      0.2
// @author       rjf89
// @match        https://gist.github.com/search*
// @grant        none
// ==/UserScript==

function getDate(e) {
  return new Date(e.querySelector('time-ago').getAttribute('datetime'));
}

function addSortButtons(elem) {
  const sortBar = elem.querySelector('div.sort-bar');
  elem.insertBefore(createSortButton('Sort Ascending', true), sortBar);
  elem.insertBefore(createSortButton('Sort Descending', false, 'margin-left: 10px'), sortBar);
}

function sortList(selector, ascending) {
  const original = document.querySelector(selector);
  const clone    = original.cloneNode(false);

  clone.appendChild(original.querySelector('div.sort-bar').cloneNode(true));
  addSortButtons(clone);
  [...original.querySelectorAll('div.gist-snippet')]
    .sort((a, b) => getDate(ascending ? a : b) - getDate(ascending ? b : a))
    .forEach(e => clone.appendChild(e));
  clone.appendChild(original.lastChild);
  original.parentNode.replaceChild(clone, original);
}

function createSortButton(text, ascending, style) {
  const sortButton = document.createElement('button');
  sortButton.type = 'button';
  sortButton.style = style;
  sortButton.classList.add('btn');
  sortButton.onclick = function() { sortList('div.column.three-fourths', ascending); };
  sortButton.textContent = text;
  return sortButton;
}

addSortButtons(document.querySelector('div.column.three-fourths'));