DownloadAchievementImages.user.js

// ==UserScript==
// @name         Download Achievement Images
// @namespace    http://tampermonkey.net/
// @version      0.1.4
// @description  Button to mass download achievement images
// @author       lylat
// @match        https://steamcommunity.com/stats/*/achievements*
// @icon         https://cdn.discordapp.com/avatars/749437490883985499/7c4053deed909ec48be2656da4b12b76.png
// @require      https://cdnjs.cloudflare.com/ajax/libs/jszip/3.1.5/jszip.min.js
// @require      https://cdnjs.cloudflare.com/ajax/libs/FileSaver.js/2.0.0/FileSaver.min.js
// @grant        GM_xmlhttpRequest
// @connect      cdn.cloudflare.steamstatic.com
// @connect      cdn.akamai.steamstatic.com
// ==/UserScript==

(()=>
{
    'use strict';
    const zip = new JSZip();
    const dlBtn = document.createElement('a');
    dlBtn.innerHTML = '<span>Download Achievement Images</span>';
    dlBtn.classList.add('tabOn');
    document.querySelector('#achievementsTabOn')?.appendChild(dlBtn);
    dlBtn.addEventListener('click', ()=> {
        const achImgs = [...document.querySelectorAll('.achieveRow')];
        let count = 0;

        achImgs.forEach(i => {
            GM_xmlhttpRequest ({
                method: 'GET',
                url: i.querySelector('.achieveImgHolder > img').src,
                responseType: 'blob',
                onload: (r) => {
                    const achName = i.querySelector('.achieveTxtHolder > .achieveTxt > h3')?.innerText.replace(/\\|\/|:|\*|\?|"|<|>|\|/, '');
                    const filename = achName.length > 100 ? achName.slice(0, 100) + '...' : achName;
                    zip.file(`${filename}.jpg`, r.response, { binary: true });

                    if(++count === achImgs.length) {
                        zip.generateAsync({ type: 'blob' }).then(c => {
                            saveAs(c, document.querySelector('.profile_small_header_texture > h1')?.textContent);
                        });
                    }
                }
            });
        });
    });
})();