Tampermonkey scipt to change chat windows with a keypress

chat_changer.js

// ==UserScript==
// @name         Chat window changer
// @namespace    http://deecewan.com
// @version      0.1
// @description  try to take over the world!
// @author       David Buchan-Swanson
// @match        https://tanda.facebook.com/chat/t/*
// @grant        none
// ==/UserScript==

(function() {
  'use strict';

  document.addEventListener('keyup', e => {
    if (!e.ctrlKey) {
      // you must press alt
      return;
    }
    if (e.keyCode < 49 || e.keyCode > 57) {
      // only handle number keys (1-9)
      return;
    }
    e.preventDefault();
    const number = e.keyCode - 49;
    const items = document
      .querySelector('[aria-label="Conversation List"')
      .querySelectorAll('li');
    const selected = items[number];

    if (!selected) {
      // who knows
      return;
    }

    selected.querySelector('a').click();
  });
})();