Derpibooru Quicksave button script!

// ==UserScript==
// @name        Derpibooru Quick Save Script
// @namespace   Violentmonkey Scripts
// @match       *://derpibooru.org/*
// @grant       none
// @run-at      document-end
// @version     2.0
// @author      Scriptki77y
// @description Adds a download button to image previews on derpibooru for quick saving!
// ==/UserScript==

window.onload = () => {
    let long_filenames = true; // Download long or short file names???
    for (el of document.querySelectorAll('[class*=main] .media-box')) { // remove [class*=main] to target all images on page
        try {
            let data = el.children;
            let header = data[0];
            data = data[1].children[0];
            data = JSON.parse(data.dataset.uris);
            url = long_filenames ? data.full.replace('/img/view/', '/img/download/') : data.large.replace('/img/', '/img/download/').replace('/large', '');
            header.appendChild(new DOMParser()
                .parseFromString(`<a rel="nofollow" title="Quicksave!" href="${url}"><i class="fa fa-download"></i> QS</a>`, "text/html")
                .body
                .childNodes[0]);
        } catch (e) {
            console.error('derpibooru downloader button script: ', e);
        }
    }
};