Load image on client side

<input type="file" onchange="updateUri(event)">
<img id="output">
<script>
  function updateUri(e) {
    if (!e.target.files && !e.target.files[0]) return;

    let reader = new FileReader(); // Create render
    reader.addEventListener("load", () =>
      // On data loaded on render add result to image element
      document.querySelector('#output').src = reader.result
    );

    reader.readAsDataURL(e.target.files[0]);
  }
</script>