Download a file asynchronously with JavaScript

example.js

var url = 'https://sitecorecdn.azureedge.net/-/media/sitecoresite/images/global/logo/sitecore-logo.svg';
download(url);
// => sitecore-logo.svg will be downloaded.

var filename = 'logo.svg';
download(url, filename);
// => 'logo.svg' will be downloaded.

fileDownloadAsync.js

function downloadBlob(blob, filename) {
  var anchor = document.createElement('a');
  anchor.download = filename;
  anchor.href = blob;
  document.body.appendChild(anchor);
  anchor.click();
  anchor.remove();
}

function download(url, filename) {
  if (!filename) {
    filename = url.split('\\').pop().split('/').pop();
  }

  fetch(url, {
    headers: new Headers({
      'Origin': location.origin
    }),
    mode: 'cors'
  })
    .then(function (response) { return response.blob(); })
    .then(function (blob) {
      var blobUrl = window.URL.createObjectURL(blob);
      downloadBlob(blobUrl, filename);
    })
    .catch(function (e) { console.error(e); });
}