window.open(URL.createObjectURL(file1));

var file1 = new File(byteArrays, tempfilename, { type: contentType });

var url = window.URL.createObjectURL(file1);
var anchor = document.createElement("a");
anchor.href = url;
anchor.download = data1[0]['filename'];
    
// (C) "FORCE DOWNLOAD"
// NOTE: MAY NOT ALWAYS WORK DUE TO BROWSER SECURITY
// BETTER TO LET USERS CLICK ON THEIR OWN
anchor.click();
window.URL.revokeObjectURL(url);
document.removeChild(anchor);