You can try scrollIntoView method on window onload

window.onload=function(){
    document.getElementById("ID_OF_IMAGE").scrollIntoView();
}

I think you looking for something like that:

window.addEventListener('load', function() {
    document.querySelector(".classFromImage").focus();
})

What you could do is search for the img element with the autofocus attribute and set the focus after the DOM is read. You also need to set the tabindex to get that working.

I would only search for img[autofocus] so that you don't mess too much around with the default behavior.

window.addEventListener('DOMContentLoaded', function() {
  let elm = document.querySelector("img[autofocus]")
  if (elm) {
    elm.focus()
  }
})

img {
  width: 100px;
  height: 100px;
  display: inline-block;
}

:focus {
  border: 4px solid red;
}

<img autofocus tabindex="0">