JavaScript でデータ URL を BLOB に変換するにはどうすればよいですか?

<code class="javascript">function dataURItoBlob(dataURI) {
  const byteString = atob(dataURI.split(',')[1]);
  const mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0];

  const ab = new ArrayBuffer(byteString.length);
  const ia = new Uint8Array(ab);

  for (let i = 0; i < byteString.length; i++) {
    ia[i] = byteString.charCodeAt(i);
  }

  const blob = new Blob([ab], { type: mimeString });
  return blob;
}</code>

<code class="javascript">const dataURL = 'data:image/png;base64,...';
const blob = dataURItoBlob(dataURL);</code>