Saving image to local storage from canvas

Question

Hi I am trying to save to file from canvas, but cannot name the file, this works but saves a file as "download" I would like give it any name. Any help is appreciated, lc.getImage gets image from canvas.

  $('#download_btn').click(function() {
     var image = lc.getImage();
     document.location.href = image.toDataURL("image/png").replace("image/png", "image/octet-stream");
  });