In the latest filesaver documentation, an example is given for how to use filesaver.js in conjunction with blobbuilder.js:
var bb = new BlobBuilder(); bb.app
wll it looks like I found the answer, although I havent tested it yet
var blob = new Blob(["Hello, world!"], {type: "text/plain;charset=utf-8"}); saveAs(blob, "hello world.txt");
from this page https://github.com/eligrey/FileSaver.js