app.js

import Elm from './src/Main.elm'

const container = document.querySelector('.container')
const elmApp = Elm.embed(Elm.Main, container)

function playSound(soundName) {
  // this is never called
  console.log('soundName is', soundName)
}

elmApp.ports.playSound.subscribe(playSound)

Main.elm

update : Action -> Model -> (Model, Effects Action)
update action model =
  case action of
    Actions.PlaySound soundName ->
      ( model, sendToJs soundName )
    Actions.NoOp ->
      ( model, Effects.none )
    Actions.SetAngel showing ->
      let
        updatedModel = {model | showingAngels = showing }
        effect = (
            if showing == True then
              clearAngel
            else
              Effects.none
          )
      in
        ( updatedModel, effect )


sendToJs : String -> Effects Action
sendToJs soundName =
  (Signal.send sounds.address soundName)
    |> Task.toResult
    |> Task.map
      (
        \res ->
          case res of
            Ok val ->
              Actions.SetAngel True
            Err val ->
              Actions.NoOp
      )
    |> Effects.task


sounds : Mailbox String
sounds = mailbox ""


port playSound : Signal String
port playSound = sounds.signal