Coding exercise

index.js

import $http from 'http-as-promised'
import Promise from 'bluebird'

const resolveClass = (currentCount, { room, students, next }) => {
  const studentsTwentyFiveOrOlder = students.filter(({ age }) => age > 24)
  const count = currentCount + studentsTwentyFiveOrOlder.length

  if (next) {
    return $http
      .get({
        url: next,
        resolve: 'body',
        json: true
      })
      .then((nextClass) => resolveClass(count, nextClass))
  } else {
    return Promise.resolve({ count, room })
  }
}

$http
.get({
  url: 'http://challenge.broadly.com/',
  resolve: 'body',
  json: true
})
.then(({ url }) => {
  return $http
    .get({
      url,
      resolve: 'body',
      json: true
    })
})
.then(({ classes })=> {
  return Promise.map(classes, (apiClass) => {
    return $http
      .get({
        url: apiClass,
        resolve: 'body',
        json: true
      })
  })
})
.then(classes => Promise.map(classes, (apiClass) => resolveClass(0, apiClass)))
.then(classes => classes.reduce((previous, { count }) => (previous + count), 0) / classes.length)
.then((average) => console.log('the average is', average))

package.json

{
  "name": "broadly",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "broadly": "babel-node index"
  },
  "author": "@armw4",
  "license": "MIT",
  "dependencies": {
    "bluebird": "^3.3.4",
    "http-as-promised": "^1.1.0",
    "node-babel": "^0.1.2"
  }
}

Verified again node@5.9.0