userscript to navigate XKCD with J and K

xkcdnav.js

// ==UserScript==
// @name         XKCD Nav
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  move back and forth in xkcd comic with J and K
// @match        https://*.xkcd.com/*
// @grant        none
// ==/UserScript==
// main
(function() {
    'use strict';
    window.addEventListener("keydown", function(event) {
        if (event.key == 'j' || event.key == 'J') {
            const bts = document.querySelectorAll('[rel="next"]')
            if (bts.length > 0) {
                bts[0].click();
            }
        } else if (event.key == 'k' || event.key == 'K') {
            const bts = document.querySelectorAll('[rel="prev"]')
            if (bts.length > 0) {
                bts[0].click();
            }
        }

    }, true);

    window.addEventListener("load", function() {
        document.querySelector('#ctitle').scrollIntoView();
    }, false);
})();