javascript & google api : array work only debug mode

Question

I don't understand why my code only works on debug mode. my variable musiques in my function createMusicBox() is an object in debug mode and null in not debuging

var musiques = [];

/**
 * Create an OAuth2 client with the given credentials, and then execute the
 * given callback function.
 *
 * @param {Object} credentials The authorization client credentials.
 * @param {function} callback The callback to call with the authorized client.
 */
function authorize(credentials, callback) {
  var clientSecret = credentials.installed.client_secret;
  var clientId = credentials.installed.client_id;
  var redirectUrl = credentials.installed.redirect_uris[0];
  var auth = new googleAuth();
  var oauth2Client = new auth.OAuth2(clientId, clientSecret, redirectUrl);

  // Check if we have previously stored a token.
  fs.readFile(TOKEN_PATH, function(err, token) {
    if (err) {
      getNewToken(oauth2Client, callback);
    } else {
      oauth2Client.credentials = JSON.parse(token);
      callback(oauth2Client);
    }
  });
}


/**
 * Lists the names and IDs of up to 10 files.
 *
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
function listFiles(auth) {
  var service = google.drive('v3');
  service.files.list({
    auth: auth,
    pageSize: 10,
    fields: "nextPageToken, files(id, name)"
  }, function(err, response) {
    if (err) {
      console.log('The API returned an error: ' + err);
      return;
    }
    var files = response.files;
    if (files.length == 0) {
      console.log('No files found.');
    } else {
      musiques=files;
      console.log('Files:');
      for (var i = 0; i < files.length; i++) {
        musiques[i] = files[i];
        var file = files[i];
        console.log('%s (%s)', file.name, file.id);
      }
    }
  });
}

// this function pulls music in my google drive

function createMusicBox() {

    // Load client secrets from a local file.
    fs.readFile('client_secret.json', function processClientSecrets(err, content) {
      if (err) {
        console.log('Error loading client secret file: ' + err);
        return;
      }
      // Authorize a client with the loaded credentials, then call the Drive API.
      authorize(JSON.parse(content), listFiles);
    });

    console.log(musiques);
}

Answer 1

I find a solution, i put a callback in listFiles and now it works perfectly

function createMusicBox(event) {
    // Load client secrets from a local file.
    fs.readFile('client_secret.json', function processClientSecrets(err, content) {
      if (err) {
        console.log('Error loading client secret file: ' + err);
        return;
      }
      // Authorize a client with the loaded credentials, then call the Drive API.
      authorize(JSON.parse(content), listFiles, event);
    });
  }

function getNewToken(oauth2Client, callback) {
  var authUrl = oauth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES
  });
  console.log('Authorize this app by visiting this url: ', authUrl);
  var rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
  });
  rl.question('Enter the code from that page here: ', function(code) {
    rl.close();
    oauth2Client.getToken(code, function(err, token) {
      if (err) {
        console.log('Error while trying to retrieve access token', err);
        return;
      }
      oauth2Client.credentials = token;
      storeToken(token);
      callback(oauth2Client);
    });
  });
}


function listFiles(auth, callback, event) {
  var service = google.drive('v3');
  service.files.list({
    auth: auth,
    pageSize: 10,
    fields: "nextPageToken, files(id, name)"
  }, function(err, response, listMusic) {
    if (err) {
      console.log('The API returned an error: ' + err);
      return;
    }
    var files = response.files;
    if (files.length == 0) {
      console.log('No files found.');
    } else {
      callback(event, files);
    }
  });
   }