Promise based Facebook Event ID scraper

Event.js

'use strict'

let Promise = require('bluebird')
let _ = require('lodash')

class Event {
  constructor(session) {
    this.session = session;
    this.scrapedIDs = [];
  }

  /*
   * Parse guests and cursor hash from response
   */
  parseGuestsAndCursor(body, guestType) {
    let ids, json;

    json = JSON.parse(body.substring(9));
    ids = json['payload'][guestType]['sections'][2][1].map((user) => user['uniqueID']);

    return {
      ids: _.uniq(ids),
      cursor: json['payload'][guestType]['cursor']
    }
  }

  cursorRequest(cursor, eventID, guestType) {
    return new Promise((resolve, reject) => {
      let url = `https://facebook.com/events/typeahead/guest_list/?event_id=${eventID}&tabs[0]=${guestType}&order[${guestType}]=affinity&bucket_schema[${guestType}]=friends&cursor[${guestType}]=${cursor}&dpr=1&__user=${this.session.uid}&__a=1`;

      this.session.request(url, (err, resp, body) => {
        if(err) {
          reject(err)
          return;
        }

        let guests;
        try {
          guests = this.parseGuestsAndCursor(body, guestType);
        } catch(err) {
          reject(err);
          return;
        }

        resolve(guests);
      })
    })
  }

  queryCursor(cursor, eventID, guestType) {
    return this.cursorRequest(cursor, eventID, guestType).then((guests) => {
        if(guests.ids.length > 0) {
          let lastIDCount = this.scrapedIDs.length;
          guests.ids.forEach((id) => this.scrapedIDs.push(id));
          this.scrapedIDs = _.uniq(this.scrapedIDs);

          /*
           * Compare the lastIDCount with the new id count after ID's have
           * been added. If they're the same this means there's no more ID's
           * left to scrape.
           */
          if(lastIDCount === this.scrapedIDs.length) {
            return Promise.resolve(this.scrapedIDs);
          }

          return this.queryCursor(guests.cursor, eventID, guestType);
        }
    })
  }

  members(eventID, guestType) {
    let ids = [];

    return new Promise((resolve, reject) => {
      let url = `https://facebook.com/events/typeahead/guest_list/?event_id=${eventID}&tabs[0]=watched&tabs[1]=going&tabs[2]=invited&order[declined]=affinity&order[going]=affinity&order[invited]=affinity&order[maybe]=affinity&order[watched]=affinity&order[ticket_purchased]=affinity&bucket_schema[watched]=friends&bucket_schema[going]=friends&bucket_schema[invited]=friends&bucket_schema[ticket_purchased]=friends&dpr=1&__user=${this.session.uid}&__a=1`;

      this.session.request(url, (err, resp, body) => {
        if(err) {
          reject(err);
          return;
        }

        let guests;
        try {
          guests = this.parseGuestsAndCursor(body, guestType);
        } catch(err) {
          reject(err);
          return;
        }

        this.queryCursor(guests.cursor, eventID, guestType)
        .then(ids => resolve(ids));
      })
    })
  }
}

module.exports = Event;