Pricewatch strikethrough

// ==UserScript==
// @name         Pricewatch strikethrough
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://tweakers.net/categorie/*
// @grant        GM_registerMenuCommand
// @grant        GM_unregisterMenuCommand
// @grant        GM_setValue
// @grant        GM_getValue
// ==/UserScript==

(function() {

    'use strict';
    function handler() {
        var li = document.getElementsByClassName('facetCount');
        for(var i=0; i<li.length; i++){
            if(mode){
                li[i].parentNode.parentNode.style.display = li[i].innerText == '0' ? 'none' : '';
            }
            else {
                if(li[i].parentNode.getElementsByClassName('facetLabel').length > 0){
                    li[i].parentNode.getElementsByClassName('facetLabel')[0].style.textDecoration = li[i].innerText == '0' ? 'line-through red' : '';
                }
            }
        }
    }

    function menu() {
        mode = !mode;
        GM_setValue('mode', mode);
        GM_unregisterMenuCommand(id);
        id = GM_registerMenuCommand(modes[+mode], menu);
    }

    function checkHash(cb) {
        if(hash == location.hash) {
            return;
        }
        hash = location.hash;
        cb();
    }

    var mode = GM_getValue('mode', false);
    var modes = ['Remove', 'Strikethrough'];
    var hash = location.hash;
    var id = GM_registerMenuCommand(modes[+mode], menu);

    //window.addEventListenter('hashchange', handler, false);
    window.setInterval(checkHash, 500, handler);

})();