YTDownloader.js

var config = require('./config.json');
var YoutubeMp3Downloader = require('youtube-mp3-downloader');

var Downloader = function() {

    var self = this;

    // Configure YoutubeMp3Downloader with your settings
    self.YD = new YoutubeMp3Downloader({
        'ffmpegPath': config.ffmpegPath,
        'outputPath': config.musicFolderPath,
        'youtubeVideoQuality': 'highest',
        'queueParallelism': 2,
        'progressTimeout': 2000
    });

    self.callbacks = {};

    self.YD.on('finished', function(data) {
        if (self.callbacks[data.videoId]) {
            self.callbacks[data.videoId](null, data);
        } else {
            console.log('Error: No callback for videoId!');
        }
    });

    self.YD.on('error', function(error) {
        console.log(error);
    });
};

Downloader.prototype.getMP3 = function(track, callback) {
    var self = this;
    // Register callback
    self.callbacks[track.videoId] = callback;
    // Trigger download
    self.YD.download(track.videoId, track.name);
};

module.exports = new Downloader();