download-sb-asset.js

function forceDownload(blob, filename) {
  var a = document.createElement('a');
  a.download = filename;
  a.href = blob;
  a.click();
}

// Current blob size limit is around 500MB for browsers
function downloadResource(url, filename) {
  if (!filename) 
    filename = url.split('\\').pop().split('/').pop()
    url = url.replace('a.storyblok', 's3.amazonaws.com/a.storyblok')
    fetch(url, {
      headers: new Headers({
      'Origin': location.origin
      }),
      mode: 'cors'
    })
    .then(response => response.blob())
    .then(blob => {
    let blobUrl = window.URL.createObjectURL(blob);
    forceDownload(blobUrl, filename);
  })
  .catch(e => console.error(e));
}

downloadResource('https:///a.storyblok.com/f/39898/2560x1438/b6646724e1/visual_editor.jpg');