js_of_ocaml, not a fan of stdio

build.sh

$ ocamlbuild foo.byte
Finished, 3 targets (0 cached) in 00:00:00.
$ js_of_ocaml foo.byte
$ node foo.js                                                                                                                                                                                                                                                     /tmp/foo

/tmp/foo/foo.js:185
i=ak(r);if(0===i){if(!m)throw D;var
                              ^
248,End_of_file,-5

foo.ml

let () =
  input_line stdin
  |> output_string stdout