Can Intersection Observer be used for lazy loading videos

Step-by-Step Implementation

1. HTML Structure: Create the HTML structure for the video elements, including a placeholder image and the actual video tag. For example:

html
<div class="video-wrap" data-video-url="video_url.mp4" data-video-title="Video Title">
  <img src="placeholder_image.jpg" class="lazy-video" alt="Video Placeholder">
  <video controls poster="placeholder_image.jpg"></video>
</div>

2. JavaScript Implementation: Use the Intersection Observer API to detect when the video element comes into view. When the video is in view, load the video dynamically by replacing the placeholder image with the actual video element.

javascript
function initVimeo() {
  const videoWraps = document.querySelectorAll(".video-wrap[data-video-url]");
  const videoStateMap = new Map();
  const observer = new IntersectionObserver((entries) => {
    entries.forEach(({ target, isIntersecting }) => {
      if (isIntersecting && !videoStateMap.get(target)) {
        const videoUrl = target.getAttribute("data-video-url");
        const videoTitle = target.getAttribute("data-video-title");
        const iframe = document.createElement("iframe");
        iframe.src = videoUrl;
        iframe.frameBorder = "0";
        iframe.allow = "autoplay; fullscreen; picture-in-picture";
        iframe.allowfullscreen = "";
        if (videoTitle) {
          iframe.title = videoTitle;
        }
        iframe.style = "position: absolute; inset: 0; width: 100%; height: 100%";
        target.appendChild(iframe);
        videoStateMap.set(target, true);
      }
    });
  }, {
    root: null,
    rootMargin: "0px",
    threshold: 0.5,
  });

  videoWraps.forEach((videoWrap) => {
    videoStateMap.set(videoWrap, false);
    observer.observe(videoWrap);
  });
}

Browser Support

The Intersection Observer API is supported in Edge, Firefox, Chrome, and Opera. For older browsers that don't support this feature, you can use feature detection to load the videos immediately.

Libraries and Tools

There are several libraries and tools available to help with lazy loading videos, including:

1. vanilla-lazyload: A lightweight library that uses Intersection Observer for lazy loading.
2. lozad.js: Another lightweight library that uses Intersection Observer for lazy loading.
3. yall.js: A library that uses Intersection Observer and falls back to event handlers for lazy loading.
4. react-lazyload: A React-specific library for lazy loading images and videos.

These libraries can help simplify the implementation of lazy loading videos and provide additional features and customization options.