Userscript to open links to PDF files on a new tab

pdf-new-tab.user.js

// ==UserScript==
// @name         PDF new tab
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://*/*
// @match        http://*/*
// @icon         data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    document.querySelectorAll('a[href*=".pdf"]').forEach(el => {
        el.setAttribute('target','_blank');
        var expression = /https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)/gi;
        var regex = new RegExp(expression);
        var t = el.getAttribute('href');
        var match = expression.exec(t);
        if (match[0]) {
            el.setAttribute('href', match[0]);
        }
    });
})();