let download filename content =
  let a =
    H.a
      [| HA.href ("data:text/plain;charset=utf-8," ^ URI.encode content)
      ;  HA.download filename
      ;  HA.style "display:none"
      |]
      [| |]
  in
  let () = Element.append_child Document.body a in
  let () = Element.click a in
  Element.remove_child Document.body a