图片js

<img data-src="image.jpg" class="lazyload" />

document.addEventListener("DOMContentLoaded", function() {
  var lazyImages = [].slice.call(document.querySelectorAll("img.lazyload"));
  if ("IntersectionObserver" in window) {
    let lazyImageObserver = new IntersectionObserver(function(entries, observer) {
      entries.forEach(function(entry) {
        if (entry.isIntersecting) {
          let lazyImage = entry.target;
          lazyImage.src = lazyImage.dataset.src;
          lazyImage.classList.remove("lazyload");
          lazyImageObserver.unobserve(lazyImage);
        }
      });
    });
    lazyImages.forEach(function(lazyImage) {
      lazyImageObserver.observe(lazyImage);
    });
  } else {
    // Fallback for browsers that don't support IntersectionObserver
    // Implement a scroll or resize handler to trigger loading of images when they are in view.
  }
});