// ==UserScript==
// @name         Ninja Button - Duolingo Japanese
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Add a "Ninja Button" to access Duolingo's Japanese course while using a web browser. 
// @author       mca62511
// @domain       duolingo.com
// @domain       www.duolingo.com
// @match        https://www.duolingo.com/*
// @match        https://duolingo.com/*
// @match        http://www.duolingo.com/*
// @match        http://duolingo.com/*
// @grant        none
// @locale       en
// @require      https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js
// @downloadURL none
// ==/UserScript==

(function() {
    'use strict';
    var $ninjaButton = $('<li class="language-choice " data-value="ja"><a href="javascript:;"><span class="flag flag-svg-micro flag-ja" style="background: url(\'http://res.cloudinary.com/mca62511/image/upload/r_3000/v1495271437/up1spqr_mcwwgi.png\') !important; background-size: contain !important;"></span><span data-value="ja">Ninja</span></a></li>');
    $("ul.dropdown-menu").append($ninjaButton);
    $ninjaButton.hide();
    $(".topbar-username").hover(function(){
        $ninjaButton.hide();
    });
    $(".topbar-language").hover(function(){
        $ninjaButton.show();
    });
    // Your code here...
})();