Simple and lightweight vk.com music download enabler userscript for Greasemonkey

vkmusic.user.js

// ==UserScript==
// @name        VK Music Download
// @namespace   bo33b
// @description Simple and lightweight VK music download enabler.
// @downloadURL https://gist.github.com/bo33b/092f3c0cdb47365ffd9d/raw/vkmusic.user.js
// @version     3.4
// @include     http://vk.com/*
// @include     https://vk.com/*
// @grant       none
// ==/UserScript==

setInterval(function() {
  var audio = document.getElementsByClassName("play_btn_wrap"), i = audio.length-1, node, file, song, a;
  for (; !audio[i].previousElementSibling && i>-1; i--) {
    node = audio[i].parentNode;
    file = node.getElementsByTagName("input")[0].value.split("?")[0];
    song = node.nextElementSibling.textContent.slice(0,-20).trim().replace("–","-")+".mp3";
    a = document.createElement("a");
    a.setAttribute("onclick","event.cancelBubble=1;");
    a.style     = "float:left;font-size:large;margin: 5px -13px";
    a.title     = "Right-click, \"Save Link As...\" to download";
    a.target    = "_blank";
    a.innerHTML = "♫";
    a.download  = song;
    a.href      = file;
    node.insertBefore(a,node.childNodes[1]);
  }
},1100);