On-demand Youtube embedded player

Hugely improves load speed of pages with lots of embedded Youtube videos by instantly showing clickable and immediately accessible placeholders, then the thumbnails are loaded in background.

Ajankohdalta 27.4.2015. Katso uusin versio.

// ==UserScript==
// @name          On-demand Youtube embedded player
// @description   Hugely improves load speed of pages with lots of embedded Youtube videos by instantly showing clickable and immediately accessible placeholders, then the thumbnails are loaded in background.
// @version       1.0.6
// @author        wOxxOm
// @namespace     wOxxOm.scripts
// @license       MIT License
// @grant         GM_addStyle
// @grant         GM_xmlhttpRequest
// @run-at        document-start
// ==/UserScript==

var resizeToFit = true;
var embedSelector = 'iframe[src*="youtube.com/embed"], embed[src*="youtube.com/v"]';

GM_addStyle('\
    .instant-youtube-container:not(small) {position:relative; overflow:hidden; cursor:pointer; background-color:black}\
    .instant-youtube-container:not(small) .instant-youtube-thumbnail {transition:opacity 0.1s ease-out; opacity:0}\
    .instant-youtube-container:not(small) .instant-youtube-play-button {position:absolute; left:0; right:0; top:0; bottom:0; margin:auto; width:85px; height:60px}\
    .instant-youtube-container:not(small) .instant-youtube-loading-button {position:absolute; left:0; right:0; top:0; bottom:0; margin:auto; display:block; width:20px; height:20px; background: url("data:image/gif;base64,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")}\
    .instant-youtube-container:hover:not(small) .ytp-large-play-button-svg {fill:#CC181E}\
    .instant-youtube-container:not(small) .instant-youtube-link {\
      position:absolute; top:50%; left:0; right:0; width:20em; height:1.7em; margin:60px auto;\
      display:block; text-align:center; text-decoration:none; color:white; text-shadow:1px 1px 3px black;\
    }\
    .instant-youtube-container:not(small) .instant-youtube-link:hover { color:white; text-decoration:underline; background:transparent }\
    .instant-youtube-container:not(small) .instant-youtube-embed {position:absolute; left:0; top:0}\
    .instant-youtube-container:not(small) .instant-youtube-link2 {\
      display:none; z-index:9; background-color:rgba(0,0,0,0.5); color: white;\
      width:100%; height: 1.7em; top:0; left:0; right:0; position:absolute; z-index: 9;\
      font-size:11pt; color:white; text-shadow:1px 1px 2px black; text-align:center; text-decoration:none;\
      margin:0; padding:0.5em 0.5em 0.2em;\
    }\
    .instant-youtube-container:not(small):hover .instant-youtube-link2 {display:block}\
    .instant-youtube-container:not(small) .instant-youtube-link2:hover {text-decoration:underline}\
');

processNodes(null, document.querySelectorAll(embedSelector));
setMutationHandler(document, embedSelector, processNodes);

function processNodes(observer, nodes) {
  for (var i=0, nl=nodes.length, n; i<nl && (n=nodes[i]); i++) {
    if (!n.parentNode || n.className.indexOf('instant-youtube-') >= 0 || n.src.indexOf('autoplay=1') > 0)
      continue;

    var id = n.src.match(/(?:embed\/|v[=\/])(.+?)(?:[&?\/].*|$)/);
    if (!id)
      continue;
    id = id[1];

    for (var np=n.parentNode, npw; np && !(npw=np.clientWidth); np=np.parentNode) {}
    var containerWidth = resizeToFit ? npw : n.clientWidth;
    var containerHeight = resizeToFit ? npw / 16 * 9 : n.clientHeight;

    var div = document.createElement('div');
    div.className = 'instant-youtube-container';
    div.srcEmbed = n.src;
    div.style.maxWidth = containerWidth + 'px';
    div.style.height = containerHeight + 'px';

    var img = div.appendChild(document.createElement('img'));
    img.className = 'instant-youtube-thumbnail';
    img.src = 'https://i.ytimg.com/vi' + (window.chrome?'_webp':'') + '/' + id + '/maxresdefault.' + (window.chrome?'webp':'jpg');
    if (n.clientHeight) {
      img.style.maxWidth = 'auto';
      img.style.width = (containerHeight / 9 * 16) + 'px';
      img.style.marginLeft = Math.round((containerWidth - containerHeight / 9 * 16) / 2) + 'px';
    }
    img.title = 'Shift-click to play directly as HTML5 video\n(sometimes buggy: playback starts only after the entire video is loaded)';
    img.onload = function(e) {
      var img = e.target;
      if (img.naturalWidth <= 120)
        img.onerror(e);
      else {
        if (img.src.indexOf('maxresdefault') < 0)
          img.style.marginTop = ((img.parentNode.clientHeight - img.clientHeight) / 2).toFixed(1) + 'px';
        img.style.setProperty('opacity', '1');
      }
    }
    img.onerror = function(e) {
      var img = e.target;
      if (img.src.indexOf('maxresdefault') > 0)
        img.src = img.src.replace('maxresdefault','hqdefault');
      else if (img.src.indexOf('hqdefault.webp') > 0)
        img.src = img.src.replace('_webp','').replace('.webp','.jpg');
    };

    div.insertAdjacentHTML('beforeend', '\
        <svg class="instant-youtube-play-button"><path fill-rule="evenodd" clip-rule="evenodd" fill="#1F1F1F" class="ytp-large-play-button-svg" d="M84.15,26.4v6.35c0,2.833-0.15,5.967-0.45,9.4c-0.133,1.7-0.267,3.117-0.4,4.25l-0.15,0.95c-0.167,0.767-0.367,1.517-0.6,2.25c-0.667,2.367-1.533,4.083-2.6,5.15c-1.367,1.4-2.967,2.383-4.8,2.95c-0.633,0.2-1.316,0.333-2.05,0.4c-0.767,0.1-1.3,0.167-1.6,0.2c-4.9,0.367-11.283,0.617-19.15,0.75c-2.434,0.034-4.883,0.067-7.35,0.1h-2.95C38.417,59.117,34.5,59.067,30.3,59c-8.433-0.167-14.05-0.383-16.85-0.65c-0.067-0.033-0.667-0.117-1.8-0.25c-0.9-0.133-1.683-0.283-2.35-0.45c-2.066-0.533-3.783-1.5-5.15-2.9c-1.033-1.067-1.9-2.783-2.6-5.15C1.317,48.867,1.133,48.117,1,47.35L0.8,46.4c-0.133-1.133-0.267-2.55-0.4-4.25C0.133,38.717,0,35.583,0,32.75V26.4c0-2.833,0.133-5.95,0.4-9.35l0.4-4.25c0.167-0.966,0.417-2.05,0.75-3.25c0.7-2.333,1.567-4.033,2.6-5.1c1.367-1.434,2.967-2.434,4.8-3c0.633-0.167,1.333-0.3,2.1-0.4c0.4-0.066,0.917-0.133,1.55-0.2c4.9-0.333,11.283-0.567,19.15-0.7C35.65,0.05,39.083,0,42.05,0L45,0.05c2.467,0,4.933,0.034,7.4,0.1c7.833,0.133,14.2,0.367,19.1,0.7c0.3,0.033,0.833,0.1,1.6,0.2c0.733,0.1,1.417,0.233,2.05,0.4c1.833,0.566,3.434,1.566,4.8,3c1.066,1.066,1.933,2.767,2.6,5.1c0.367,1.2,0.617,2.284,0.75,3.25l0.4,4.25C84,20.45,84.15,23.567,84.15,26.4z M33.3,41.4L56,29.6L33.3,17.75V41.4z"></path><polygon fill-rule="evenodd" clip-rule="evenodd" fill="#FFFFFF" points="33.3,41.4 33.3,17.75 56,29.6"></polygon></svg>\
        <a class="instant-youtube-link" href="https://www.youtube.com/watch?v=' + id + '" target="_blank"><b>Watch on Youtube</b></a>\
        <span class="instant-youtube-link" style="margin-top:6em">Watch as HTML5</span>\
    ');

    n.parentNode.insertBefore(div, n);
    n.remove();

    div.addEventListener('click', function clickHandler(e) {
      if (e.target.href)
        return;
      for (var div = e.target; !div.srcEmbed; div = div.parentNode) {}
      var iframeHTML = '<iframe class="instant-youtube-embed" src="' + div.srcEmbed + (div.srcEmbed.indexOf('?') > 0 ? '' : '?') +
          '&autoplay=1' +
          '&autohide=2' +
          '&border=0' +
          '&controls=1' +
          '&fs=1' +
          '&showinfo=1' +
          '&ssl=1' +
          '&theme=dark' +
          '" frameborder="0" allowfullscreen="allowfullscreen" width="' + div.clientWidth + '" height="' + div.clientHeight + '"></iframe>';
      div.removeEventListener('click', clickHandler);
      div.querySelector('svg').outerHTML = '<span class="instant-youtube-loading-button"></span>';
      
      if (!e.shiftKey && e.target.className != 'instant-youtube-link')
        div.insertAdjacentHTML('beforeend', iframeHTML);
      else {
        div.querySelector('span.instant-youtube-link').style.display = 'none';
        GM_xmlhttpRequest({
          method: 'GET',
          url: div.srcEmbed.replace(/\/(embed\/|v[=\/])/, '/watch?v='),
          onload: function(response) {
            var video;
            video = div.appendChild(document.createElement('video'));
            video.controls = true;
            video.autoplay = true;
            video.width = div.clientWidth;
            video.height = div.clientHeight;
            video.className = 'instant-youtube-embed';
            
            var m;
            if (m = response.responseText.match(/ytplayer\.config\s*=\s*(\{.+?\});/)) {
              var cfg = JSON.parse(m[1]), streams = {};
              cfg.args.url_encoded_fmt_stream_map.split(',').forEach(function(stream){
                var params = {}
                stream.split('&').forEach(function(kv){ params[kv.split('=')[0]] = decodeURIComponent(kv.split('=')[1]) });
                streams[params.itag] = params;
              });
              cfg.args.fmt_list.split(',').forEach(function(fmt){
                var itag = fmt.split('/')[0], dimensions = fmt.split('/')[1], stream = streams[itag];
                if (stream) {
                  var source = video.appendChild(document.createElement('source'));
                  source.src = stream.url;
                  source.title = stream.quality + ', ' + dimensions + ', ' + stream.type;
                }
              });
            } else {
              var rx = /url=([^=]+?mime%3Dvideo%252F(?:mp4|webm)[^=]+?)(?:,quality|,itag|.u0026)/g;
              var text = response.responseText.split('url_encoded_fmt_stream_map')[1];
              while (m = rx.exec(text)) {
                video.appendChild(document.createElement('source')).src = decodeURIComponent(decodeURIComponent(m[1]));
              }
            }
            if (video.children.length) {
              if (window.chrome) {
                video.addEventListener('click', function(e) { if (e.target.paused) {e.target.play()} else {e.target.pause()} });
              }
              var title = response.responseText.match(/<title>(.+?)(?:\s*-\s*YouTube)?<\/title>/);
              if (title) {
                var a = div.querySelector('.instant-youtube-link');
                a.innerHTML = '<b>' + title[1] + '</b> - watch on Youtube';
                a.className = 'instant-youtube-link2';
              }
              div.querySelector('img').style.display = 'none';
            } else {
              video.remove();
              div.insertAdjacentHTML('beforeend', iframeHTML);
            }
          }
        });
      } 
    });
  }
  
  return true;
}

function setMutationHandler(baseNode, selector, cb) {
  var ob = new MutationObserver(function(mutations){
    for (var i=0, ml=mutations.length, m; (i<ml) && (m=mutations[i]); i++)
      for (var j=0, nodes=m.addedNodes, nl=nodes.length, n; (j<nl) && (n=nodes[j]); j++)
        if (n.nodeType == 1) 
          if ((n = n.matches(selector) ? [n] : n.querySelectorAll(selector)) && n.length)
            if (!cb(ob, n))
              return;
  });
  ob.observe(baseNode, {subtree:true, childList:true}); 
}