Userscript: VocaDB button to open PV thumbnail in new tab

VocaDB-PV-thumbnail-button.user.js

// ==UserScript==
// @name        VocaDB PV thumbnail button
// @namespace   https://gist.github.com/alanrme/6dc32bfb67d61937d81d7bfbfdf15adf
// @icon
// @version     1.2.0
//
// @match       *://vocadb.net/S/*
// @match       *://www.vocadb.net/S/*
// @grant       none
//
// @author      Alan D'souza
// @description Adds a button to open PV thumbnails in a new tab on VocaDB
//
// @run-at      document-idle
// ==/UserScript==

// This is really hacked together!!!!!

function addButton(thumb) {
  // find original "play" button on pv thumbnail and make a clone
  playButton = thumb.getElementsByTagName("button")[0];
  imgButton = playButton.cloneNode(true);
  // change the svg inside the clone button, give it an offset to not overlap with the play button
  imgButton.getElementsByTagName("span")[0].innerHTML = `<svg aria-hidden="true" width="20" height="20" viewBox="0 0 16 16" fill="currentColor" class="___12fm75w f1w7gpdv fez10in fg4l7m0" xmlns="http://www.w3.org/2000/svg"><g id="SVGRepo_bgCarrier" stroke-width="0"></g><g id="SVGRepo_tracerCarrier" stroke-linecap="round" stroke-linejoin="round"></g><g id="SVGRepo_iconCarrier"> <path fill-rule="evenodd" clip-rule="evenodd" d="M1 1H15V15H1V1ZM6 9L8 11L13 6V13H3V12L6 9ZM6.5 7C7.32843 7 8 6.32843 8 5.5C8 4.67157 7.32843 4 6.5 4C5.67157 4 5 4.67157 5 5.5C5 6.32843 5.67157 7 6.5 7Z" fill="#000000"></path> </g></svg>`;
  imgButton.style.left = "56px";

  thumb.insertBefore(imgButton, playButton.nextSibling);

  // open the thumbnail in a new tab when clone img button is pressed
  imgButton.addEventListener('click', function() {
    window.open(thumb.getElementsByTagName("div")[0].style.backgroundImage.slice(4, -1).replace(/"/g, ""));
  });
}

// create observer to see if pv thumbnail element has loaded in
const observer = new MutationObserver((mutations, obs) => {
    const target = document.getElementsByClassName('pv-embed-preview')[0];
    if (target) {
        obs.disconnect(); // stop watching
        addButton(target);
    }
});
// start observing the document body
observer.observe(document.body, {
    childList: true,
    subtree: true
});

I only tested this on Chromium 151