E621 Sound/Epilepsy warning

// ==UserScript==
// @name             E621 Sound/Epilepsy warning
// @description      Temporarily blocks potentially harmful content, I (Chessax) hereby release this into the public domain free of use for any purpose.
// @include          http*://e621.net/post/show/*
// @grant            none
// ==/UserScript==

//Tags to filter, 'message' key is optional
var entries = [
  {
    tag: 'epilepsy_warning',
    message: 'flashing or strobing lights or fast or disorienting movements'
  },
  {
    tag: 'sound_warning',
    message: 'loud sound'
  }
]

//window.onload = function tagWarning(){
var tagList = document.getElementById('post_tags').value;
var header = '<h1>Warning!</h1><br /><p>This post has been tagged with ';
var tags = '';
var message = '';
for (var i = 0; i < entries.length; ++i){
  if ((new RegExp('\\b'+entries[i].tag+'\\b').test(tagList))){
    tags += '<i>' + entries[i].tag + '</i>, ';
    if (typeof entries[i].message != 'undefined' && entries[i].message != '' && entries[i].message != null){
     message += entries[i].message + '; ';
    }
  }
}
tags = tags.slice(0, -2);
if (message.length > 0){
  message = ' and may contain:<br />' + message.slice(0, -2) + '.';
}
else{
  message = '.';
}
var footer = '<br />Viewer discretion is advised.</p>';

var width, height;
var found = false;
//Image
var img = document.getElementById('image')
if (img) {
  found = true;
  width = img.clientWidth;
  height = img.clientHeight;
}
//SWF
if (!found) {
  var imgs = document.getElementsByTagName('param')
  for (var i = 0; i < imgs.length; ++i) {
    if (/e621\.net\/data\//.test(imgs[i].value)) {
      found = true;
      img = imgs[i].parentNode;
      width = img.width;
      height = img.height;
      break;
    }
  }
}
//WebM
if (!found) {
  img = document.getElementById('webm-container');
  if (img) {
    found = true;
    width = img.clientWidth;
    height = img.clientHeight;
  }
}
if (!found) {
  var script = document.createElement('script')
  script.setAttribute('type', 'text/javascript');
  script.textContent = '(warning(\'Sound/Epilepsy warning is broken, please contact user script developer (not e621 developer)\'))();';
  document.body.appendChild(script);
  document.body.removeChild(script);
  return;
}

var outer = document.createElement('div');
outer.style.minWidth = Math.max(350, width) + 'px';
outer.style.minHeight = Math.max(200, height) + 'px';
outer.style.width = '0px';
outer.style.height = '0px'
outer.style.textAlign = 'center';
outer.style.display = 'flex';
outer.style.alignItems = 'center';
outer.style.border = '1px solid white';
var inner = document.createElement('div');
inner.style.margin = '20px';
inner.style.width = '100%';
var warning = document.createElement('div');
warning.innerHTML = header + tags + message + footer;
var button = document.createElement('button');
button.innerHTML = 'Understood'
button.addEventListener('click', function () {
  outer.parentNode.removeChild(outer);
  img.style.display = '';
});
inner.appendChild(warning);
inner.appendChild(button);
outer.appendChild(inner);
img.parentNode.insertBefore(outer, img.parentNode.firstChild)
img.style.display = 'none';
//}