Spotify Magic 🎩. A sample webtask endpoint

package.json

{
 "dependencies": {
   "spotify-web-api-node": "2.5.0"
 }
}

source.js

var SpotifyApi = require('spotify-web-api-node');

var CLIENT_ID = 'fb1aec35307d496ca35006b97cc09ced';
var CLIENT_SECRET = '8ce3c1ca8b5c479cb5d2eec4fef7dcb9';
var REDIRECT_URI = 'https://dayspring.com.co';
var REFRESH_TOKEN = 'AQCAHij2FfDyGUp4fxODSLMmeqBcK7Hy-bvLDoqqiqLsWxLjh2VHtq6AjkOgoj5k4T6ROF5U3XXMjlCzWTNV2hZcb9gnDn8wwRvbROrVqzsvWqQ_xq03CU3PJpYvv5YqENU';

var spotifyApiClient = new SpotifyApi({
  clientId : CLIENT_ID,
  clientSecret : CLIENT_SECRET,
  redirectUri : REDIRECT_URI,
  refreshToken: REFRESH_TOKEN
});

module.exports = function (context, cb) {

  var artistName = context.query.name;
  if (!artistName) {
    console.log('No name parameter provided');
    return cb(null, `Please provide an artist name via the \'name\' URL parameter.`);
  }

  spotifyApiClient.refreshAccessToken()
  .then(function(data) {
    spotifyApiClient.setAccessToken(data.body['access_token']);
    return spotifyApiClient.searchArtists(artistName);
  }).then(function(searchResultsData) {
    return fetchTopTracksFromSearchResultsData(searchResultsData);
  }).then(function(topTracksData) {
    var trackIDs = getTrackIDsFromData(topTracksData.body.tracks);
    return spotifyApiClient.getAudioFeaturesForTracks(trackIDs);
  }).then(function(tracksAudioFeaturesData) {
    var aggregateAudioFeatures = processAudioFeaturesFromData(tracksAudioFeaturesData);
    return cb(null, aggregateAudioFeatures);
  }, function(err) {
    console.error(err);
    cb(null, `An error occured ${err.toString()}`);
  });
}

/**
 * @param {Object} searchResultsData The search results data
 * @return {Object} The top tracks with the provided data's artist ID
 */
function fetchTopTracksFromSearchResultsData(searchResultsData) {
  var artists = searchResultsData.body.artists.items;
  if (artists.length > 0 && artists[0].id.length > 0) {
    var topArtist = artists[0];
    return spotifyApiClient.getArtistTopTracks(topArtist.id, 'US');
  } else {
    return Promise.resolve('Your search returned no results');
  }
}

/**
 * @param {Object} tracksData The track's data
 * @return {Array} An array of track IDs
 */
function getTrackIDsFromData(tracksData) {
  var trackIDs = [];
  for (i = 0; i < tracksData.length; i++) {
    if (tracksData[i].id && tracksData[i].id.length > 0) {
      trackIDs.push(tracksData[i].id);
    } else {
      console.log(`No id for object: ${JSON.stringify(tracksData[i])}`);
    }
  }
  return trackIDs;
}

/**
 * @param {Object} audioData The aggregate tracks' audio data
 * @return {Object} An aggregate data object resulting from the mean of the main track attributes
 */
function processAudioFeaturesFromData(audioData) {

  var audioFeatures = audioData.body.audio_features;

  if (!audioFeatures.length) {
    console.log(`No tracks found for data ${audioData.body}`);
    return[];
  }

  var overallDanceability = 0;
  var overallEnergy = 0;
  var overallInstrumentalness = 0;
  var overallLiveness = 0;
  var overallTempo = 0;
  var overallSpeechiness = 0;

  for (i = 0; i < audioFeatures.length; i++) {
    overallDanceability += audioFeatures[i].danceability;
    overallTempo += audioFeatures[i].tempo;
    overallSpeechiness += audioFeatures[i].speechiness;
    overallLiveness += audioFeatures[i].liveness;
    overallEnergy += audioFeatures[i].energy;
    overallInstrumentalness += audioFeatures[i].instrumentalness;
  }

  overallInstrumentalness /= audioFeatures.length;
  overallDanceability /= audioFeatures.length;
  overallTempo /= audioFeatures.length;
  overallSpeechiness /= audioFeatures.length;
  overallLiveness /= audioFeatures.length;
  overallEnergy /= audioFeatures.length;

  return {
    overallEnergy: overallEnergy,
    overallLiveness: overallLiveness,
    overallTempo: overallTempo,
    overallSpeechiness: overallSpeechiness,
    overallDanceability: overallDanceability,
    overallInstrumentalness: overallInstrumentalness
  };
}