How do I save an audio to a folder with gtts using javascript?

Question

I am writing a Javascript program and need to save an audio file using gtts or any other sound library. My code:

var texto = "Preciso ser um arquivo de áudio";
var filepath = "mp3/song.wav";

gtts.save(filepath, texto, function() {
console.log(`${filepath} MP3 SALVO`)
});