HTMLImageElement: naturalHeight

<div class="box">
  <img
    src="/ja/docs/Web/HTML/Reference/Elements/img/clock-demo-400px.png"
    class="image"
    alt="" />
</div>
<pre></pre>

.box {
  width: 200px;
  height: 200px;
}

.image {
  width: 100%;
}

const output = document.querySelector("pre");
const image = document.querySelector("img");

image.addEventListener("load", (event) => {
  const { naturalWidth, naturalHeight, width, height } = image;
  output.textContent = `
: ${naturalWidth} x ${naturalHeight} 
: ${width} x ${height} 
`;
});