Force download of BLOB

gistfile1.js

// Create URL to download the blob file
var url = URL.createObjectURL(blob);

// Create hidden anchor and click it to initiate the download
a = document.createElement('a');
document.body.appendChild(a);
a.style = 'display: none';
a.href = url;
a.download = conn.metadata.filename;
a.click();
URL.revokeObjectURL(url);