Nodejs script using polly API to return an audio stream (through a promise)

polly_audiogeneration.js

// Generate audio from Polly and check if output is a Buffer
const generatePollyAudio = (text, voiceId) => {
  const params = {
    Text: text,
    OutputFormat: 'mp3',
    VoiceId: voiceId // see Polly API for the list http://docs.aws.amazon.com/fr_fr/polly/latest/dg/API_Voice.html#API_Voice_Contents
  }

  return polly.synthesizeSpeech(params).promise().then( audio => {
    if (audio.AudioStream instanceof Buffer) return audio
    else throw 'AudioStream is not a Buffer.'
  })
}