Project Euler: Translate Into Japanese (Tampermonkey, Greasemonkey?)

userscript.js

// ==UserScript==
// @name         Project Euler: Translate Into Japanese
// @namespace    https://gist.github.com/45deg/5551106ee5aa24f39e1d
// @version      0.1
// @description  odz.sakura.ne.jp/projecteuler/ から日本語訳を取ってきて追加するスクリプト
// @author       zakuro
// @run-at       document-end
// @match        https://projecteuler.net/problem=*
// @grant        GM_xmlhttpRequest
// ==/UserScript==

GM_xmlhttpRequest({
    method: "GET",
    url: "http://odz.sakura.ne.jp/projecteuler/index.php?cmd=read&page=Problem%20" + location.href.match(/\d+$/)[0],
    onload: function(response) {
        var responseXML = new DOMParser().parseFromString(response.responseText, "text/html");
        var paragraphs = responseXML.querySelectorAll('#body > *');

        var problemContent = document.getElementsByClassName('problem_content')[0];
        // add horizonal line
        problemContent.appendChild(document.createElement('hr'));
        // add japanese problem content
        for (var i = 1; i < paragraphs.length; i++) {
            problemContent.appendChild(paragraphs[i]);
        }
    }
});