Via JavaScript Strictly, No. 
But here are two alternatives, 1 client side and 1 server side.
Force Download via HTM5 link.
Now the
  HTML5
  spec defines a very useful download attribute on hyperlinks that
  basically allows to force download behavior on client-side, regardless
  of what comes in Content-Type and Content-Disposition from the server.
Fiddled Here: http://jsfiddle.net/qmwxt/
<a href="URL" download> Download your Question</a>
Read more here: https://stackoverflow.com/a/15970140/144665
Set Content-Disposition in the header.
Or if you have server side control set Content-Disposition in the header which forces the save dialog.
Read more here: How to encode the filename parameter of Content-Disposition header in HTTP?