// ==UserScript==
// @name         AO3: Use Left/Right Arrow-Keys to Navigate
// @namespace    https://greasyfork.org/en/users/906106-escctrl
// @version      1.0
// @description  use the left/right arrow keys to jump between pages, chapters, works in a series
// @author       escctrl
// @match        https://*.archiveofourown.org/*
// @grant        none
// @require      https://ajax.googleapis.com/ajax/libs/jquery/3.7.0/jquery.min.js
// @license      MIT
// @downloadURL none
// ==/UserScript==

(function($) {
    'use strict';

    // this uses the first of whichever is encountered:
    // (A) the "jump to page" links at the top of lists, like on works/bookmarks listings, tag search results, etc
    // (B) then the chapters in a work
    // (C) and finally the works in a series
    // meaning that if you're on chapter 1 of work #3 in a series, pressing the left-arrow key will take you to work #2 in the series
    // if a work is in multiple series, it's not quite reliable because it will use the first one that shows up in the metadata
    let page_prev = $('.pagination .previous a, .work.navigation .chapter.previous a, .work.meta .series a.previous');
    let page_next = $('.pagination .next a, .work.navigation .chapter.next a, .work.meta .series a.next');

    $(document).keydown(function(event){
        var key = event.which;
        switch(key) {
            case 37: // Key left.
                if (page_prev.length > 0) window.location.assign(page_prev[0].href);
                break;
            case 39: // Key right.
                if (page_next.length > 0) window.location.assign(page_next[0].href);
                break;
            default:
                break;
        }
    });

})(jQuery);