natokeys.user.js

// ==UserScript==
// @name         NATO Nav Keys
// @namespace    http://roub.net/
// @version      1.0
// @description  'j'/'k' to scroll to next/previous NATO answers. 'q' to scroll from an answer to its question when NATO Enhancements are in play. 'v' to open the currently-selected answer in a new window/tab.
// @author       paulroub
// @match        /https?:\/\/(meta\.)?stackoverflow.com\/tools\/new-answers-old-questions.*/
// @include      /https?:\/\/(meta\.)?stackoverflow.com\/tools\/new-answers-old-questions.*/
// @updateURL    https://gist.github.com/paulroub/8ce3e8bc72d50213d2c81b0823322c29/raw/natokeys.user.js
// @grant        none
// ==/UserScript==
/* eslint-env jquery */
'use strict';

(function() {
    const b = $(document.body);

    b.keypress( function(e) {
        var tag = e.target.tagName.toLowerCase(),
            c = String.fromCharCode(e.which),
            ib, it, i,
            st = Math.ceil($(window).scrollTop()),
            as = null,
            noQ = false,
            nextTop = -1,
            prevTop = -1,
            currentTop = -1,
            scrollTo = -1,
            currentTopAnswer = [],
            a;

        // ignore actual j, k, q in comments, etc.
        if ( tag == 'input' || tag == 'textarea') {
          return;
        }

        if ((c == 'j') || (c == 'k') || (c == 'q') || (c == 'v'))
        {
            as = $('.answer');

            // no .answer matches == NATO enhancements not in use (or not yet)
            // look for the unmodified answers and skip the 'q' key
            if (as.length < 1)
            {
                var pt = $('.post-text');
                noQ = true;

                as = pt.get().map(
                    function(p) {
                        return $(p).closest('td');
                    }
                );
            }
        }

        for ( i = 0; i < as.length; ++i )
        {
            a = $(as[i]);
            it = Math.floor(a.offset().top);
            ib = it + a.height();

            if ((it > st) && (nextTop < 0))
            {
                nextTop = it;
            }
            else if (ib <= st)
            {
                prevTop = it;
            }

            if ((ib >= st) && (currentTop < 0) && ! noQ)
            {
                const q = a.closest('tr').find('h1');
                currentTop = q.offset().top;
                currentTopAnswer = a.find('.js-share-link');
            }
        }

        switch (c)
        {
            case 'j':
                scrollTo = nextTop;
                break;

            case 'k':
                scrollTo = prevTop;
                break;

            case 'q':
                scrollTo = currentTop;
                break;

            case 'v':
                if (currentTopAnswer.length > 0) {
                    const href = currentTopAnswer.attr('href');
                    window.open(href);
                }
                break;
        }

        if (scrollTo >= 0)
        {
            $('html, body').animate({
                scrollTop: scrollTo
            }, 250);
        }
    });
})();