https://github.com/stripe/stripe-node/blob/master/lib/utils.js#L232

callbackify.js

const callbackifyPromiseWithTimeout = function(promise, callback) {
    if (callback) {
      // Ensure callback is called outside of promise stack.
      return promise.then(function(res) {
        setTimeout(function() { callback(null, res) }, 0);
      }, function(err) {
        setTimeout(function() { callback(err, null); }, 0);
      });
    }

    return promise;
  }