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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

HTML

              
                <main>
  <section>

    <h1>Late-load YouTube videos on demand</h1>

    <p>Videos are loaded upon user interaction, not before.</p>
    <p>A lightweight, accessible, and very performant, video component / module using HTML5 Custom Elements. Just the background image is loaded until it's showtime.
    </p>

  </section>



  <section>

    <h2>Single video</h2>

    <yt-l class=vdo-1 hidden videoId=631k3M2Sxe4 videoTitle="Rock &amp; Bowl festival"></yt-l>

  </section>



  <section class=-fullWidthBlock>

    <h2>Multiple videos <span>(in a block)</span></h2>

    <!-- 
        Note: This is a list of four list items.
              Use a ul, ol, or add roles to divs.
    -->
    <div class=video_lst role=list>

      <!-- Classes are used for layout -->
      <yt-l class=vdo-2 hidden role=listitem videoId=vzbXU-MhghA videoTitle="Bat the Dog: Sweet About Me"></yt-l>

      <yt-l class=vdo-2 hidden role=listitem videoId=CIqM2oCru5U videoTitle="The Go Nows: Best Laid Plans"></yt-l>

      <yt-l class=vdo-2 hidden role=listitem videoId=57hvbJkd_fc videoTitle="Bat the Dog: La Bamba"></yt-l>

      <yt-l class=vdo-2 hidden role=listitem videoId=aNjyxudde40 videoTitle="Shalane: Jammin' on the beach"></yt-l>

    </div>

  </section>



  <section>

    <h2>Built with WCAG Accessibility in mind</h2>
    <ul>
      <li>Friendly to keyboard-only users</li>
      <li>Accessible names are used throughout</li>
      <li>The play button is labelled</li>
      <li>The iframe includes a title</li>
      <li>Each asset has a heading</li>
      <li>Fully responsive</li>
      <li>Customisable via CSS variables (Custom Properties)</li>
      <li>Smoother transition between static image and video.</li>
    </ul>

    <h2>Why bother to do this?</h2>
    <p>See the well-thought-out article: <a class=-nowrap target=_blank title="[new window]" href="https://lean.codecomputerlove.com/make-your-own-lightweight-youtube-player/">Make YouTube Embeds Load Faster</a> by Moujib Aghrout. His reasoning is very good, though personally I'd use the method presented here.</p>

  </section>


  <section>

    <h2>That beautiful code!</h2>
    
    <p>See the CodePen panels for annotation, this is the production friendly nitty-gritty:</p>

    <figure>
      <figcaption>HTML single video</figcaption>
      <pre><code class=language-markup spellcheck=false contenteditable>&lt;yt-l videoId="[youtube-id]" videoTitle="[video-title]"&gt;&lt;/yt-l&gt;</code></pre>
    </figure>

    <figure>
      <figcaption>HTML multiple video block</figcaption>
      <pre><code class=language-markup spellcheck=false contenteditable>&lt;div role="list"&gt;
  &lt;yt-l role="listitem" videoId="[youtube-id]" videoTitle="[video-title]"&gt;&lt;/yt-l&gt;
  &lt;yt-l role="listitem" videoId="[youtube-id]" videoTitle="[video-title]"&gt;&lt;/yt-l&gt;
  &hellip;
&lt;/div&gt;</code></pre>
    </figure>

    <figure>
      <figcaption>CSS Custom Properties</figcaption>
      <pre><code class=language-css spellcheck=false contenteditable>yt-l {
  /* Exposed "globally-scoped" custom properties: */
  /* These are the default values */
  /* They don't need to be defined, and may be overridden */
  --aspectRatio: calc(100% / (16 / 9));
  --overlayBgImg: linear-gradient(0, rgba(0,0,0,.4) 6%, rgba(0,0,0,0) 50%, rgba(0,0,0,.4) 100%);
  --btnSize: 3rem;
  --titleColor: #fff;
  --titleBgColor: #000;
  --titleFont: 1rem/1 sans-serif;
  --titlePadding: .25rem;
}</code></pre>
    </figure>

    <figure>
      <figcaption>JavaScript ES6 <small>[5.22 KB - 2.58 KB gzipped]</small></figcaption>
      <pre><code class=language-js spellcheck=false contenteditable>const template=document.createElement('template');template.innerHTML=`<style>:host{--aspectRatio:calc(100% / (16 / 9));--overlayBgImg:linear-gradient(0, rgba(0,0,0,.4) 6%, rgba(0,0,0,0) 50%, rgba(0,0,0,.4) 100%);--btnHeight:3rem;--titleColor:#fff;--titleBgColor:#000;--titleFont:1rem/1 sans-serif;--titlePadding:.25rem;display:block;position:relative;contain:content;cursor:pointer}.ytl::before,.ytl_btn-play,.ytl_svg{position:absolute}.ytl::before{content:'';width:100%;height:100%;background-image:var(--overlayBgImg);transition:opacity .3s ease-out}.ytl:focus-within::before,.ytl:hover::before{opacity:0}.ytl::after{content:"";display:block;padding-bottom:var(--aspectRatio)}.ytl_btn-play::-moz-focus-inner{border:0}.ytl_btn-play{display:block;width:100%;height:100%;background-color:transparent;border:none;padding:0;cursor:pointer}.ytl_svg{display:block;top:50%;left:50%;width:calc(var(--btnHeight) * 1.42);height:var(--btnHeight);transform-origin:50% 50%;z-index:1;transform:translate3d(-50%,-50%,0)}.ytl_iframe,.ytl_title{position:absolute;width:100%}.ytl_path-playBg{fill:hsla(0,0%,0%,.5);transition:fill .3s ease-out}.ytl_btn-play:focus .ytl_path-playBg,.ytl_btn-play:hover .ytl_path-playBg{fill:hsla(0,100%,50%,1);outline:0}.ytl_title{bottom:0;color:var(--titleColor);background-color:var(--titleBgColor);font:var(--titleFont);text-align:center;margin:0;padding:var(--titlePadding);transition:opacity .3s ease-out,visibility 0s ease-out .3s}.ytl_iframe{height:100%;top:0;left:0;opacity:0;transition:opacity 1s ease-out}.-js-loading .ytl_svg{transform:translate3d(-50%,-50%,0) scale(1.6);opacity:.7}.ytl_path-loading{display:none;transform-origin:50% 50%;animation:rotating 1s linear infinite}.-js-loading .ytl_path-loading{display:block}.-js-loading .ytl_path-play{display:none}@keyframes rotating{from{transform:rotate(0)}to{transform:rotate(360deg)}}.-js-loaded{cursor:unset}.-js-loaded>.ytl_iframe{opacity:1}.-js-loaded::before,.-js-loaded>.ytl_btn-play,.-js-loaded>.ytl_title{visibility:hidden;opacity:0}</style>`;
class YouTubeLiteEmbed extends HTMLElement{constructor(){super(),this.attachShadow({mode:"open"});const e=this.shadowRoot;e.appendChild(template.content.cloneNode(!0)),e.videoId=encodeURIComponent(this.getAttribute("videoid")),e.heading=this.getAttribute("videoTitle")?encodeURIComponent(this.getAttribute("videoTitle")):"Play video",e.posterUrl=`https://i.ytimg.com/vi/${e.videoId}/hqdefault.jpg`,YouTubeLiteEmbed.addPrefetch("preload",e.posterUrl,"image")}connectedCallback(){const e=this.shadowRoot;this.style.backgroundImage=`url("${e.posterUrl}")`;let t=e.querySelector(".ytl");t||this.addWrapper(),(t=e.ytl).heading||this.addHeading(),t.querySelector(".lty-playbtn")||this.addButton(),t.addEventListener("pointerover",YouTubeLiteEmbed.warmConnections,{once:!0}),t.playBtn.addEventListener("click",e=>{t.classList.add("-js-loading"),this.addIframe()})}static addPrefetch(e,t,o){const d=document.createElement("link");d.rel=e,d.href=t,o&&(d.as=o),d.crossorigin=!0,document.head.append(d)}static warmConnections(){YouTubeLiteEmbed.preconnected||(YouTubeLiteEmbed.addPrefetch("preconnect","https://www.youtube-nocookie.com"),YouTubeLiteEmbed.addPrefetch("preconnect","https://www.google.com"),YouTubeLiteEmbed.addPrefetch("preconnect","https://googleads.g.doubleclick.net"),YouTubeLiteEmbed.addPrefetch("preconnect","https://static.doubleclick.net"),YouTubeLiteEmbed.preconnected=!0)}addWrapper(){const e=this.shadowRoot,t=document.createElement("div");t.className="ytl",e.appendChild(t),e.ytl=t}addHeading(){const e=this.shadowRoot,t=document.createElement("h3");t.id=decodeURIComponent(e.videoId),t.className="ytl_title",t.textContent=decodeURIComponent(e.heading),e.ytl.heading=t,e.ytl.appendChild(t)}addButton(){const e=this.shadowRoot,t=document.createElement("button");t.type="button",t.classList.add("ytl_btn-play"),t.setAttribute("aria-label","Play video: "+decodeURIComponent(e.heading)),t.setAttribute("aria-pressed",!1),t.innerHTML='\n<svg class=ytl_svg viewBox="0 0 68 48" aria-hidden=true focusable=false><g class=ytl_path-play><path class=ytl_path-playBg d="M66.52,7.74c-0.78-2.93-2.49-5.41-5.42-6.19C55.79,.13,34,0,34,0S12.21,.13,6.9,1.55 C3.97,2.33,2.27,4.81,1.48,7.74C0.06,13.05,0,24,0,24s0.06,10.95,1.48,16.26c0.78,2.93,2.49,5.41,5.42,6.19 C12.21,47.87,34,48,34,48s21.79-0.13,27.1-1.55c2.93-0.78,4.64-3.26,5.42-6.19C67.94,34.95,68,24,68,24S67.94,13.05,66.52,7.74z"/><path d="M 45,24 27,14 27,34" fill=#fff /></g><circle class=ytl_path-loading cx=34 cy=24 r=18 fill=none stroke=#fff stroke-dasharray="60 30" stroke-width=4 transform="rotate(190 34 24)"/></svg>',e.ytl.playBtn=t,e.ytl.appendChild(t)}addIframe(){const e=this.shadowRoot,t=`\n<iframe class=ytl_iframe title="${decodeURIComponent(e.heading)}" frameborder=0 allowfullscreen allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture"\nsrc="https://www.youtube-nocookie.com/embed/${e.videoId}?autoplay=1"></iframe>`;e.ytl.insertAdjacentHTML("beforeend",t);const o=e.querySelector(".ytl_iframe");o.addEventListener("load",t=>{setTimeout(t=>{e.ytl.classList.add("-js-loaded")},1e3)},{once:!0}),o.focus()}}
customElements.define('yt-l', YouTubeLiteEmbed);
</code></pre>
    </figure>

  </section>


  <section>
    <h2>Alternative solutions</h2>
    <p class=tagline>This is Version 3 which is heavily based on the Paul Irish project: <a class=-nowrap target=_blank title="[new window]" href="https://github.com/paulirish/lite-youtube-embed">Lite YouTube Embed</a>, but updated to meet WCAG Accessibility requirements.</p>
    
    <p>There's also a pen of <a target=_blank title="[new window]" href="https://codepen.io/2kool2/pen/dyoJrav">Version 2</a> which was loosely based around <a target=_blank title="[new window]" href="https://www.cssscript.com/load-youtube-video-thumbnail-lazytube/">LazyTube</a> and doesn't use Custom Elements.</p>
    
    <p>Another method worthy of serious consideration is: <a class=-nowrap target=_blank title="[new window]" href="https://dev.to/haggen/lazy-load-embedded-youtube-videos-520g">Lazy load embedded YouTube videos</a> by Arthur Corenzan.</p>

    <p>Personally, if you can get away from YouTube as a hosting solution, I prefer <a target=_blank title="[new window]" href="https://codepen.io/2kool2/pen/WNvywpB?editors=1000">Cloud CDN-hosted video</a> using <a class=-nowrap target=_blank title="[new window]" href="https://cloudinary.com/">Cloudinary</a> or <a class=-nowrap target=_blank title="[new window]" href="https://www.netlify.com/">Netlify</a> and the HTML video element. Far less data transferred, and easier to embed.</p>

    <h2>Credits</h2>
    <p>Videos courtesy of <a class=-nowrap target=_blank title="[new window]" href="http://batthedog.uk/">Bat the Dog</a></p>
    <p>Font-size, and spacing, calculation generated by: <a class=-nowrap target=_blank title="[new window]" href="https://websemantics.uk/tools/responsive-font-calculator/">Fluid-responsive font-size calculator</a></p>
    <p>Code blocks: <a class=-nowrap target=_blank title="[new window]" href="https://codepen.io/2kool2/pen/MEbeEg">Code highlighting with Prism.js</a></p>
    <p>Embedding code: <a class=-nowrap target=_blank title="[new window]" href="https://websemantics.uk/tools/escaping-html/">Escaping HTML symbols/entities</a></p>
  </section>

</main>



<!-- Codepen footer include -->
[[[https://codepen.io/2kool2/pen/mKeeGM]]]
              
            
!

CSS

              
                /* Generic page styles */

:root {

  /* Fluidly variable between: 16px @ 320px and 32px @ 1920px */
  --space: calc(1rem + ((1vw - 0.2em) * 1));

  --spaceDouble: calc(var(--space) * 2);
  --spaceTwoThirds: calc(var(--space) / 1.5);
  --spaceHalf: calc(var(--space) / 2);
  --spaceThird: calc(var(--space) / 3);
  --spaceQuarter: calc(var(--space) / 4);

  --maxTextWidth: 35em;

  --colorF: #f5f5f5;
  --colorE: #e5e5e5;
  --colorD: #d5d5d5;
  --bgColor0: #0a0a0a;
  --bgColor1: #1a1a1a;
  --bgColor2: #2a2a2a;

  font-size: var(--space);
  line-height: 1.7;
  max-width: 120rem;
  margin: 0 auto;
}
@media (min-width: 120em) {
  :root {
    --space: 2rem;
  }
}
body {
  color: var(--colorD);
  background-color: var(--bgColor0);
  background-image: url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg'%3E%3Cdefs%3E%3Cfilter id='a'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.7'/%3E%3C/filter%3E%3C/defs%3E%3Crect filter='url(%23a)' opacity='.3' width='100%25' height='100%25'/%3E%3C/svg%3E");
  background-attachment: fixed;
  margin: var(--space);
  font-family: sans-serif;
}
h1 {
  font-size: 1.5rem;
  font-weight: 100;
  line-height: 1.2;
  margin: 0 0 var(--spaceHalf);
}
h2 {
  font-size: 1.25rem;
  font-weight: 100;
  line-height: 1.2;
  margin: var(--spaceDouble) 0 0;
}
h2 > span {font-size:smaller}
h3 {
  font-size: 1rem;
  font-weight: 100;
  line-height: 1.2;
}
section {
  max-width: var(--maxTextWidth);
  margin-left: auto;
  margin-right: auto;
}
.-fullWidthBlock {
  max-width: none;
}
p, ul {margin: var(--spaceTwoThirds) 0  0}
li {margin: var(--spaceQuarter) 0  0}
p, li {
  font-weight: 100;
}
.-nowrap {white-space:nowrap}


/* Fancier text links */
body {
  --fancyColor: hsla(214,72%,48%,1);
  --fancyColorHover: hsla(214,72%,20%,1);
  --fancyBgHover: hsla(214,100%,80%,1);
  --fancyUnderline: hsla(214,72%,48%,1);
}
@media (prefers-color-scheme: dark) {
  body:not([data-lightMode="light"]) {
    --fancyColor: hsla(214,100%,72%,1);
    --fancyColorHover: #fff;
    --fancyBgHover: hsla(214,100%,25%,1);
    --fancyUnderline: hsla(214,100%,72%,.4);
  }
}
body[data-lightMode="dark"] {
  --fancyColor: hsla(214,100%,72%,1);
  --fancyColorHover: #fff;
  --fancyBgHover: hsla(214,100%,25%,1);
  --fancyUnderline: hsla(214,100%,72%,.4);
}
/* Fancy links */
a:link,
a:visited {
  color: var(--fancyColor);
  white-space: nowrap;
  position: relative;
  text-decoration: none;
  border-bottom: 1px solid var(--fancyUnderline);
  transition: color .3s ease-out;
}
a:hover,
a:focus {
  color: var(--fancyColorHover);
}
a::before,
a::after {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
  opacity: .5;
  transform: scaleX(0);
  transition: all .2s;
}
a::before {
  background-color: var(--fancyBgHover);
  outline-offset: -.25rem;
  outline: var(--fancyBgHover) solid .5rem;
  height: 100%;
  bottom: 0;
  z-index: -1;
}
a::after {
  background-color: var(--fancyColor);
  bottom: -0.1rem;
  height: 0.1rem;
}
a:hover::before,
a:focus::before,
a:hover::after,
a:focus::after {
  opacity: 1;
  transform: scaleX(1);
}

/* Grid layout */

.video_lst {
  --columns: 1fr;
  display: grid;
  grid-gap: var(--space);
  grid-template-columns: var(--columns);
  list-style: none;
  margin: var(--spaceHalf) 0 0;
  padding: 0;
}
@media(min-width: 50em) { /* 800px */
  .video_lst {
    --columns: 1fr 1fr;
  }
}


/* Video Players */
[class^="vdo-"] {
  background-color: #000;
  background-position: center center;
  background-size: cover;
  transition: box-shadow .3s ease-out;
}
/* I prefer interactive content to "come forwards" on hover or focus - hence the drop-shadow */
[class^="vdo-"]:hover,
[class^="vdo-"]:focus-within {
  box-shadow: 0 .25rem .25rem hsla(0,0%,0%,0.5);
}
.vdo-1 {
  margin: var(--spaceTwoThirds) 0  0;
}


/* The component / module */
yt-l {
  opacity:0;
  transition: opacity 3s ease-out 1s;
/* Exposed "globally-scoped" custom properties: */
/* These are the default values */
/* May be overwritten, but do not require defining here */

  --aspectRatio: calc(100% / (16 / 9));

  --overlayBgImg: linear-gradient(0,
    rgba(0,0,0,.4) 6%, 
    rgba(0,0,0,0) 50%, 
    rgba(0,0,0,.4) 100%
  );

  --btnHeight: 3rem;

  --titleColor: #fff;
  --titleBgColor: #000;
  --titleFont: 1rem/1 sans-serif;
  --titlePadding: .25rem;

  /* Default overrides */
  --titleFont: var(--space)/1.3 sans-serif;
  --titlePadding: var(--spaceQuarter);
}

@media(min-width: 50em) {
  yt-l.vdo-2 {
    /* Adjustments for two columns */
    --btnHeight: calc(var(--space) * 1.75);
    --titleFont: var(--spaceTwoThirds)/1.3 sans-serif;
  }
}



/* Code containers */

figure {
  max-width: var(--maxTextWidth);
  margin: var(--spaceDouble) 0;
}



/* Includes Prism code highlighting: https://codepen.io/2kool2/pen/MEbeEg */
              
            
!

JS

              
                // Force dark mode for links and code highlighting
document.body.setAttribute('data-lightMode', 'dark');


const template = document.createElement('template');
template.innerHTML = `
<style>
:host {
--aspectRatio: calc(100% / (16 / 9));

--overlayBgImg: linear-gradient(0, rgba(0,0,0,.4) 6%, rgba(0,0,0,0) 50%, rgba(0,0,0,.4) 100%);

--btnHeight: 3rem;

--titleColor: #fff;
--titleBgColor: #000;
--titleFont: 1rem/1 sans-serif;
--titlePadding: .25rem;

  display: block;
  position: relative;
  contain: content;
  cursor: pointer;
}
.ytl::before {
  content: '';
  position: absolute;
  width: 100%;
  height: 100%;
  background-image: var(--overlayBgImg);
  transition: opacity 0.3s ease-out;
}
/* Lose the bgImg shadow on hover / focus */
.ytl:focus-within::before,
.ytl:hover::before {
  opacity: 0;
}
.ytl::after {
  content: "";
  display: block;
  padding-bottom: var(--aspectRatio);
}
.ytl_btn-play::-moz-focus-inner {
  border: 0;
}
/* Button is the full size of video player */
.ytl_btn-play {
  display: block;
  position: absolute;
  width: 100%;
  height: 100%;
  background-color: transparent;
  border: none;
  padding: 0;
  cursor: pointer;
}
/* The SVG is centered to the button */
.ytl_svg {
  display: block;
  position: absolute;
  top: 50%;
  left: 50%;
  width: calc(var(--btnHeight) * 1.42);
  height: var(--btnHeight);
  transform-origin: 50% 50%;
  z-index: 1;
  transform: translate3d(-50%, -50%, 0);
}
/* Add color on hover / focus */
.ytl_path-playBg {
  fill: hsla(0,0%,0%,.5);
  transition: fill .3s ease-out;
}
.ytl_path-playBg + path {
  fill: #fff;
}
.ytl_btn-play:hover .ytl_path-playBg,
.ytl_btn-play:focus .ytl_path-playBg {
  fill: hsla(0,100%,50%,1);
  outline: none;
}
.ytl_title {
  position: absolute;
  bottom: 0;
  width: 100%;
  color: var(--titleColor);
  background-color: var(--titleBgColor);
  font: var(--titleFont);
  text-align: center;
  margin: 0;
  padding: var(--titlePadding);
  transition: opacity .3s ease-out, visibility 0s ease-out .3s;
}
.ytl_iframe {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  opacity: 0;
  transition: opacity 1s ease-out;
}

/* Iframe loading - Switch button svg from play to spinner  */

.-js-loading .ytl_svg {
  transform: translate3d(-50%, -50%, 0) scale(1.6);
  opacity: .7;
}
.ytl_path-loading {
  display: none;
  transform-origin: 50% 50%;
  animation: rotating 1s linear infinite;
}
.-js-loading .ytl_path-loading {
  display: block;
}
.-js-loading .ytl_path-play {
  display: none;
}
@keyframes rotating {
  from {transform: rotate(0deg)}
  to {transform: rotate(359deg)}
}

/* Iframe loaded - Fade in iframe and remove button and bg gradient */

.-js-loaded {
  cursor: unset;
}
.-js-loaded > .ytl_iframe {
  opacity: 1;
}
/* Remove from keychain by removing visibility */
.-js-loaded::before,
.-js-loaded > .ytl_title,
.-js-loaded > .ytl_btn-play {
  visibility: hidden;
  opacity: 0;
}
</style>`;



class YouTubeLiteEmbed extends HTMLElement {
  
  constructor() {

    super();
    this.attachShadow({mode: 'open'});
    const tsr = this.shadowRoot;
 tsr.appendChild(template.content.cloneNode(true));

    tsr.videoId = encodeURIComponent(this.getAttribute('videoid'));

    tsr.heading = this.getAttribute('videoTitle') ? encodeURIComponent(this.getAttribute('videoTitle')) : 'Play video';

    tsr.posterUrl = `https://i.ytimg.com/vi/${tsr.videoId}/hqdefault.jpg`;
    YouTubeLiteEmbed.addPrefetch('preload', tsr.posterUrl, 'image');
    
    tsr.host.style.opacity = 1;

    // Or let a late-loader handle the poster image loading (my personal preference)
    // this.setAttribute('data-LL-src', tsr.posterUrl);
  }

  connectedCallback() {

    const tsr = this.shadowRoot;

    // If late-loading the poster, remove this line
    this.style.backgroundImage = `url("${tsr.posterUrl}")`;

    let ytl = tsr.querySelector('.ytl');
    if (!ytl) this.addWrapper();
    ytl = tsr.ytl;

    if (!ytl.heading) this.addHeading();

    let playBtn = ytl.querySelector('.ytl_btn-play');
    if (!playBtn) this.addButton();

    ytl.addEventListener('pointerover', 
      YouTubeLiteEmbed.warmConnections, {once: true});

    ytl.playBtn.addEventListener('click', e => {
      ytl.classList.add('-js-loading');
      this.addIframe();
    });

  }

  static addPrefetch(kind, url, as) {
    const linkElem = document.createElement('link');
    linkElem.rel = kind;
    linkElem.href = url;
    if (as) linkElem.as = as;
    linkElem.crossorigin = true;
    document.head.append(linkElem);
  }

  static warmConnections() {
    if (YouTubeLiteEmbed.preconnected) return;
    YouTubeLiteEmbed.addPrefetch('preconnect', 'https://www.youtube-nocookie.com');
    YouTubeLiteEmbed.addPrefetch('preconnect', 'https://www.google.com');
    YouTubeLiteEmbed.addPrefetch('preconnect', 'https://googleads.g.doubleclick.net');
    YouTubeLiteEmbed.addPrefetch('preconnect', 'https://static.doubleclick.net');
    YouTubeLiteEmbed.preconnected = true;
  }

  addWrapper() {
    const tsr = this.shadowRoot;
    const ytl = document.createElement('div');
    ytl.className = 'ytl';
    tsr.appendChild(ytl);
    tsr.ytl = ytl;
  }

  addHeading() {
    const tsr = this.shadowRoot;
    const heading = document.createElement('h3');
    heading.id = decodeURIComponent(tsr.videoId);
    heading.className = 'ytl_title';
    heading.textContent = decodeURIComponent(tsr.heading);
    tsr.ytl.heading = heading;
    tsr.ytl.appendChild(heading);
  }
  
  createSVG() {
    
  }

  addButton() {
    const tsr = this.shadowRoot;
    const playBtn = document.createElement('button');
    playBtn.type = 'button';
    playBtn.classList.add('ytl_btn-play');
    playBtn.setAttribute('aria-label', 'Play video: ' + decodeURIComponent(tsr.heading));
    playBtn.setAttribute('aria-pressed', false);
    playBtn.innerHTML = `
<svg class=ytl_svg viewBox="0 0 68 48" aria-hidden=true focusable=false>
  <g class=ytl_path-play>
    <path fill=none class=ytl_path-playBg d="M66.52,7.74c-0.78-2.93-2.49-5.41-5.42-6.19C55.79,.13,34,0,34,0S12.21,.13,6.9,1.55 C3.97,2.33,2.27,4.81,1.48,7.74C0.06,13.05,0,24,0,24s0.06,10.95,1.48,16.26c0.78,2.93,2.49,5.41,5.42,6.19 C12.21,47.87,34,48,34,48s21.79-0.13,27.1-1.55c2.93-0.78,4.64-3.26,5.42-6.19C67.94,34.95,68,24,68,24S67.94,13.05,66.52,7.74z"/>
    <path d="M 45,24 27,14 27,34" fill=none />
  </g>
  <circle class=ytl_path-loading cx=34 cy=24 r=18 fill=none stroke=#fff stroke-dasharray="60 30" stroke-width=4 transform="rotate(190 34 24)"/>
</svg>
`;
    tsr.ytl.playBtn = playBtn;
    tsr.ytl.appendChild(playBtn);
  }

  addIframe() {
    const tsr = this.shadowRoot;

    // WCAG - iframes require a title
    const iframeHTML = `
<iframe class=ytl_iframe title="${decodeURIComponent(tsr.heading)}" frameborder=0 allowfullscreen allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture"
src="https://www.youtube-nocookie.com/embed/${tsr.videoId}?autoplay=1"></iframe>`;

    tsr.ytl.insertAdjacentHTML('beforeend', iframeHTML);
    const iframe = tsr.querySelector('.ytl_iframe');
    iframe.addEventListener('load', e => {
      // Wait 1 second for video to start running before fading it in
      // Allows for a smoother transition betwen static image and video.
      // Alternatively you could load the API for the playerready event but it defeats the purpose.
      setTimeout(_ => {
        tsr.ytl.classList.add('-js-loaded');
      }, 1000);
    }, {once: true});
    iframe.focus();
  }

}
customElements.define('yt-l', YouTubeLiteEmbed);



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