[%%shared

  let a_button =
    let b = Html.D.(button ~a:[a_class ["btn"]] [txt "halli hallo"]) in
    [%client (
      (Lwt.async @@ fun () ->
       let b' = Eliom_content.Html.To_dom.of_button ~%b in
       Lwt_js_events.clicks b'
         (fun _ _ ->
            b'##.innerHTML := (Js.string "GARN");
            Dom_html.window##alert(Js.string ("Garfield!"));
            Lwt.return ());
      ) : unit
    )];
    b
]