DLSite/HVDB interlinking userscripts

DLSite to HVDB.user.js

// ==UserScript==
// @name         DLSite to HVDB
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  Add link to HVDB in DLSite product pages
// @author       z411
// @match        https://www.dlsite.com/maniax/work/=/product_id/*
// @match        https://www.dlsite.com/ecchi-eng/work/=/product_id/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    var rj = window.location.href.match(/R[JE](\d{6,})/)[0];

    var title = document.getElementById("work_outline");
    title.innerHTML += "<tr><th>HVDB</th><td><a href=\"https://hvdb.me/Dashboard/WorkDetails/" + rj + "\">View in HVDB</a></td></tr>";
})();

HVDB to DLSite.user.js

// ==UserScript==
// @name         HVDB to DLSite
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  Add DLSite in HVDB work details page
// @author       z411
// @match        https://hvdb.me/Dashboard/WorkDetails/*
// @match        https://hvdb.me/Dashboard/Details/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    var basename = window.location.href.split('/').pop();
    // hvdb links can be prefixed with RE/RJ, so just get the numbers
    var rj = basename.match(/(R[JE])?([0-9]{5,})/)[2];
    rj = rj.padStart(6, '0');

    var h2 = document.getElementsByTagName("h2")[0];
    h2.innerHTML += " (DLSite <a rel=\"noreferrer\" href=\"https://www.dlsite.com/maniax/work/=/product_id/RJ" + rj + ".html\">JP</a>";
    h2.innerHTML += "/<a rel=\"noreferrer\" href=\"https://www.dlsite.com/ecchi-eng/work/=/product_id/RE" + rj + ".html\">EN</a>)"
})();