api.js

import express from 'express';
import fetchAttributes from '../services/attributes';

/* eslint new-cap: "off" */
const router = express.Router();

router.route('/tasks/:taskId/attributes')
  .get((req, res) => {
    fetchAttributes(req.params.taskId).then(responses => res.json(responses));
  });

export default router;

attributes.js

import R from 'ramda';
import callBizApi from './callBizApi';
import extractAttributes from '../util/extractAttributes';
import sumAttributes from '../util/sumAttributes';
import averageAttributes from '../util/averageAttributes';

const fetchAttributes = taskId => (
  new Promise(resolve => (
    callBizApi([`/tasks/${taskId}/responses`, `/tasks/${taskId}/questions`])
      .then(mapAttributes)
      .then(resolve)
  ))
);

export const mapAttributes = R.compose(
  averageAttributes,
  sumAttributes,
  extractAttributes
);

export default fetchAttributes;