Userscript to add j/k keyboard navigation to zerohedge

zerocruft.user.js

// ==UserScript==
// @name           ZeroCruft
// @version        1.1
// @namespace      1bae28cfed0eddb302b3ac9b578412a3
// @author         Dan Garthwaite <dan@garthwaite.org>
// @description    Removes the cruft from the new zerohedge
// @include        http://*zerohedge.com/*
// @run-at         document-end
// ==/UserScript==

(function() {
    'use strict';
    var page = document.getElementById('page');
    var sidebarLeft = document.getElementById('sidebar-left');
    var sidebarRight = document.getElementById('sidebar-right');

    page.style.maxWidth = "80em";
    page.style.marginLeft = page.style.marginRight = "auto";
    sidebarLeft.remove();
    sidebarRight.remove();

    var jk = function(a, inc) {
        if (!a.length) { return; }
        for (var i = 0; i < a.length; i++) {
            if (a[i].classList.contains('jk-current')) {
                var next = (i + inc) % a.length;
                a[i].classList.toggle('jk-current');
                a[next].classList.toggle('jk-current');
                break;
            }
        }
    };

    /* Do jk navigation */
    $('head').append('<style>.jk-current {outline: 1px solid navy;}</style>');
    var arts = document.getElementsByTagName("article");
    if (arts.length > 3) {
        arts[2].classList.add('jk-current');
        jk(arts, 1);
    }
    $(document.body).keypress(function (event) {
        // ignore keypresses in input fields
        if (document.activeElement.tagName == 'INPUT') {
            return;
        }

        if (arts.length === 0) {
            return;
        }

        var key = String.fromCharCode(event.which).toUpperCase();

        if (key === 'J' || key === ' ') { // J or space for next
            jk(arts, 1);
        } else if (key == 'K') { // K for back
            jk(arts, -1);
        } else if (key == 'O' || event.which == 13) {
            var toClick = $(".jk-current").find('a')[0];
            console.log("toClick = " + toClick);
            toClick.click();
        } else {
            return;
        }

        //scroll .jk-current to top of window
        $('html, body').animate({
            scrollTop: $(".jk-current").offset().top - 100
        }, 200);
    });
})();