masteringModule/node_modules/superagent/lib/should-retry.js

var ERROR_CODES = [
  'ECONNRESET',
  'ETIMEDOUT',
  'EADDRINFO',
  'ESOCKETTIMEDOUT'
];

/**
 * Determine if a request should be retried.
 * (Borrowed from segmentio/superagent-retry)
 *
 * @param {Error} err
 * @param {Response} [res]
 * @returns {Boolean}
 */
module.exports = function shouldRetry(err, res) {
  if (err && err.code && ~ERROR_CODES.indexOf(err.code)) return true;
  if (res && res.status && res.status >= 500) return true;
  // Superagent timeout
  if (err && 'timeout' in err && err.code == 'ECONNABORTED') return true;
  if (err && 'crossDomain' in err) return true;
  return false;
};