Download button for bandcamp.com

bandcamp-download.user.js

// ==UserScript==
// @name         Bandcamp downloader
// @namespace    Bandcamp
// @version      1.0
// @description  Adds a download button next to songs on bandcamp.com
// @author       umnikos
// @match        http*://*.bandcamp.com/*
// @license      GPL3
// @grant        GM_download
// @require      https://cdn.jsdelivr.net/npm/@violentmonkey/dom@1
// ==/UserScript==

// I have no clue how web development works. I just know there's an <audio> object in the html 
// that magically gets updated with the link to the audio file right after the user clicks on the play button
// so this code clicks on that button instead of the user and then downloads from that link
// code snippets scavenged from https://greasyfork.org/en/scripts/20719-bandcamp-download-mp3s/code

function download_song() {
  var playbutton = document.getElementsByClassName("playbutton")[0];
  playbutton.click();
  setTimeout((function() {
    playbutton.click();
  }), 0);
  var audioelement = document.getElementsByTagName("audio")[0];
  //var trackname = TralbumData.trackinfo[0].title;
  var trackname = document.getElementsByClassName("inline_player")[0].getElementsByClassName("title")[0].innerHTML;
  trackname = trackname.replace(/[^a-z0-9]/gi, ' ').replace(/\s+/g, ' ').toLowerCase();
  document.getElementById("downloadButton").innerHTML = "Downloading...";
  GM_download({
    url: audioelement.src, 
    name: trackname + ".mp3",
    onerror: (() => {document.getElementById("downloadButton").innerHTML = "Error while downloading.";}),
    ontimeout: (() => {document.getElementById("downloadButton").innerHTML = "Download timed out.";})
  });
}

(function() {
  VM.observe(document.body, () => {
    if (TralbumData) {  
      if (TralbumData.hasAudio && !TralbumData.freeDownloadPage && TralbumData.trackinfo) {
        var mydiv = document.getElementsByClassName("tralbumCommands")[0];
        var mybutton = document.createElement("a");
        mybutton.id = "downloadButton";
        mybutton.onclick = download_song;
        mybutton.classList = ["download-link", "buy-link"];
        mybutton.innerHTML = "Download for free!";
        mydiv.insertBefore(document.createElement("br"),mydiv.firstChild);
        mydiv.insertBefore(mybutton, mydiv.firstChild);
      }
      return true;
    }
  });
}());