How could JavaScript catch exceptions raised by OCaml?

Question

I have a OCaml projet, which is later converted to JavaScript by js_of_ocaml. I wrap some functions like follows:

Js.Unsafe.global##.parseFile := Js.wrap_callback
    (fun s -> Js.string (E.parse_file (Js.to_string s)));

Then, in JavaScript, I could call parseFile("abc").

In the OCaml code, for example, E.parse_file may raise exceptions by failwith "this is why". I would like to know how to catch this exception in JavaScript code, and eventually catch this is why?

try {
  parseFile("abc")
}
catch(error) {
  ???
}