Replaces the long URL with a simpler shorter one

Amazon-URL-Shortener.js

// ==UserScript==
// @name         Amazon URL Shortener
// @namespace    https://gist.github.com/Aikufurr
// @version      0.1
// @description  Replaces the long URL with a simpler shorter one
// @author       Aikufurr
// @match        https://www.amazon.co.uk/*
// @match        https://www.amazon.com/*
// @match        https://www.amazon.de/*
// @match        https://www.amazon.co.jp/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    var shortURL = /(dp\/.*?-?[^a-zA-Z0-9])/g;
    var currentURL = window.location.href;
    var website = /(amazon.*?\/)/g;
    var domain = "https://www.";
    if (!currentURL.match(website)[0].endsWith("/")){
        domain += currentURL.match(website)[0] + "/"
    } else {
        domain += currentURL.match(website)[0]
    }
    var longURL = /(amazon.*\/[a-zA-Z0-9].*\/dp)/g;
    if (longURL.test(currentURL)){
        if (shortURL.test(currentURL)){
            var newURL = domain + currentURL.match(shortURL)[0].substring(0,currentURL.match(shortURL)[0].length-1);
        } else {
            var newURL = domain + currentURL.match(/(dp.*)/g)[0].substring(0,currentURL.match(/(dp.*)/g)[0].length-1);
        }
        window.history.pushState(newURL, "Title", newURL);
    }
})();