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HTML

CSS

CSS Base

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JavaScript

Babel includes JSX processing.

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HTML

              
                <h2 class="intro">
  <span>Press the button on the right to initialize lazy loading --> </span>
  <button>Start lazy loading</button></h2>
<div class="flex">
  <div>
    <img
      data-src="https://via.placeholder.com/300x400"
      alt="Cane"
      width="300"
      height="400"
      data-srcset="https://via.placeholder.com/300x400 1x, https://via.placeholder.com/600x800 2x"
      class="lazy"
    />
  </div>
  <div>
    <img
      data-src="https://via.placeholder.com/300x400"
      alt="Cane"
      width="300"
      height="400"
      data-srcset="https://via.placeholder.com/300x400 1x, https://via.placeholder.com/600x800 2x"
      class="lazy"
    />
  </div>
  <div>
    <img
      data-src="https://via.placeholder.com/300x400"
      alt="Cane"
      width="300"
      height="400"
      data-srcset="https://via.placeholder.com/300x400 1x, https://via.placeholder.com/600x800 2x"
      class="lazy"
    />
  </div>
</div>
<p>
  Lorem ipsum dolor sit, amet
  consectetur adipisicing elit.
  Explicabo deleniti quae expedita eius
  atque quidem in possimus beatae odit
  corporis iusto quaerat temporibus quo
  quasi, sapiente aspernatur dicta quis
  ab!
</p>
              
            
!

CSS

              
                .flex {
  display: flex;
}
.flex > div {
  width: 33%;
}
img {
  width: 50%;
  height: auto;
  border: 1px solid red;
}
.intro {
  display: flex;
  justify-content: space-between;
}
button {
  font-size: 1.2rem;
  font-weight: bold;
}
              
            
!

JS

              
                document.querySelector("button").addEventListener("click", () => {
  new LazyLoad();
});
              
            
!
999px

Console