How to get the load time of two different elements on the page?

Question

I have a codepen here. There are two different YouTube embeds. One is being lazy loaded, and the other is a straight embed.

How do I determine the load time of each element to test which one works faster and by how much time?

*(The 2nd embed doesn't seem to work in Stack's code snippet tool. Please use the Codepen)

(function(){
  let YouTubeContainers = document.querySelectorAll(".embed-youtube");

  // Iterate over every YouTube container you may have
  for (let i = 0; i < YouTubeContainers.length; i++) {
    let container = YouTubeContainers[i];
    let imageSource = "https://img.youtube.com/vi/"+ container.dataset.videoId +"/sddefault.jpg"; 

    // Load the Thumbnail Image asynchronously
    let image = new Image();
    image.src = imageSource;
    image.addEventListener("load", function() {
      container.appendChild(image);
    });

    // When the user clicks on the container, load the embedded YouTube video
    container.addEventListener("click", function() {
      let iframe = document.createElement( "iframe" );

      iframe.setAttribute("frameborder", "0");
      iframe.setAttribute("allowfullscreen", "");
      iframe.setAttribute("allow", "accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture");
      // Important: add the autoplay GET parameter, otherwise the user would need to click over the YouTube video again to play it 
      iframe.setAttribute("src", `https://www.youtube.com/embed/ ${this.dataset.videoId}?rel=0&showinfo=0&autoplay=1`);

      // Clear Thumbnail and load the YouTube iframe
      this.innerHTML = "";
      this.appendChild( iframe );
    });
  }
})();

.container {
  max-width: 600px;
}

.embed-youtube {
  background-color: #000;
  margin-bottom: 30px;
  position: relative;
  padding-top: 56.25%;
  overflow: hidden;
  cursor: pointer;
}
.embed-youtube img {
  width: 100%;
  top: -16.84%;
  left: 0;
  opacity: 0.7;
}
.embed-youtube .embed-youtube-play {
  width: 68px;
  height: 48px;
  background-color: #333;
  box-shadow: 0 0 30px rgba( 0,0,0,0.6 );
  z-index: 1;
  opacity: 0.8;
  border-radius: 6px;
}
.embed-youtube .embed-youtube-play:before {
  content: "";
  border-style: solid;
  border-width: 15px 0 15px 26.0px;
  border-color: transparent transparent transparent #fff;
}
.embed-youtube img,
.embed-youtube .embed-youtube-play {
  cursor: pointer;
}
.embed-youtube img,
.embed-youtube iframe,
.embed-youtube .embed-youtube-play,
.embed-youtube .embed-youtube-play:before {
  position: absolute;
}
.embed-youtube .embed-youtube-play,
.embed-youtube .embed-youtube-play:before {
  top: 50%;
  left: 50%;
  transform: translate3d( -50%, -50%, 0 );
}
.embed-youtube iframe {
  height: 100%;
  width: 100%;
  top: 0;
  left: 0;
}

.embed-youtube .embed-youtube-play:hover {
  background-color: #f00;
}

<div class="container">
  <!-- 1. Video Wrapper Container -->
  <div class="embed-youtube" data-video-id="4_7PE7wpils">
    <!-- 2. The preview button that will contain the Play icon -->
    <div class="embed-youtube-play"></div>
  </div>  
</div>

<div class="container">
  <iframe width="100%" height="355" src="https://www.youtube.com/embed/4_7PE7wpils" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>  
</div>

Record the time when you create the element, then have the `load` event listener subtract that from the current time to get the load time. — Barmar, Jul 29 '21 at 21:02
https://stackoverflow.com/questions/29233928/iframe-onload-javascript-event — , Jul 29 '21 at 21:44

How to get the load time of two different elements on the page?

0 Answers0