如何用javascript调整图片的大小，但不改变图片的比例？

 ```

 if (originalWidth > originalHeight) {

   newHeight = (newWidth / originalWidth) * originalHeight;

 } else {

   newWidth = (newHeight / originalHeight) * originalWidth;

 }

 ```

function adjustImageSize(imageId, newWidth, newHeight) {
  var imageElement = document.getElementById(imageId);
  var originalWidth = imageElement.naturalWidth;
  var originalHeight = imageElement.naturalHeight;

  if (newWidth && !newHeight) {
    newHeight = (newWidth / originalWidth) * originalHeight;
  } else if (!newWidth && newHeight) {
    newWidth = (newHeight / originalHeight) * originalWidth;
  } else if (newWidth && newHeight) {
    if (originalWidth > originalHeight) {
      newHeight = (newWidth / originalWidth) * originalHeight;
    } else {
      newWidth = (newHeight / originalHeight) * originalWidth;
    }
  }

  imageElement.style.width = newWidth + 'px';
  imageElement.style.height = newHeight + 'px';
}

<img id="myImage" src="path/to/image.jpg" alt="My Image">

<script>
  adjustImageSize('myImage', 300, 200);
</script>