DicomWriter

// add link to html
const link = document.createElement("a");
link.appendChild(document.createTextNode("download"));
const div = document.getElementById("dwv");
div.appendChild(link);
// XMLHttpRequest onload callback
const onload = function (event) {
  const parser = new dwv.DicomParser();
  parser.parse(event.target.response);
  // create writer
  const writer = new dwv.DicomWriter();
  // get buffer using default rules
  const dicomBuffer = writer.getBuffer(parser.getDicomElements());
  // create blob
  const blob = new Blob([dicomBuffer], {type: 'application/dicom'});
  // add blob to download link
  link.href = URL.createObjectURL(blob);
  link.download = "anonym.dcm";
};
// DICOM file request
const request = new XMLHttpRequest();
const url = 'https://raw.githubusercontent.com/ivmartel/dwv/master/tests/data/bbmri-53323851.dcm';
request.open('GET', url);
request.responseType = 'arraybuffer';
request.onload = onload;
request.send();