In an effort to more intelligently request data for sent updates

analyticsStore.js

var AnalyticsStore = modules.exports = {
  
  _data: new Backbone.Collection(),
  
  _daysInCache: [],
  
  grabDaysForCache: function(data) {
    var days = data.updates.map(function(update){
      return Math.r(update.due_at / 24 / 3600); // days since 1970
    });
    var uniqueDays = _.uniq(days);
    this.addDatesToCache(uniqueDays);
    return data;
  },
  
  addDatesToCache: function(days) {
    this._daysInCache = _.uniq(this._daysInCache.concat(days));
  },

  // Splits our projected range into smaller ranges if we have some of the dates
  // in the cache
  getRangesForFetch: function(startTimestamp, days) {
    // compare with existing days
    var startDay = Math.floor(startTimestamp / 24 / 3600);
    var endDay = startDay + days;
    var ranges = [];
    var currentRange = { start: null, end: null };

    for (var day = startDay; day <= endDay; day + 24 * 3600) {
      // If the day isn't cached
      if (this._daysInCache.indexOf(day) === -1) {
        if (!currentRange.start) {
          currentRange.start = day * 24 * 3600;
        } else {
          // Continuously update the end range
          currentRange.end = day * 24 * 3600;
        }
      } else {
        // If the date is in the queue, close off the current range
        if (currentRange.end) {
          ranges.push(currentRange);
          currentRange = {};
        } else if (currentRange.start) {
          currentRange.end = currentRange.start + 24 * 3600;
          ranges.push(currentRange);
          currentRange = {};
        }
      }
    }

    // duplicated from above (could be refactored)
    if (currentRange.end) {
      ranges.push(currentRange);
    } else if (currentRange.start) {
      currentRange.end = currentRange.start + 24 * 3600;
      ranges.push(currentRange);
    }

    return ranges;
  },
  
  getData: function(startTimestamp, endTimestamp) {
    //psudo-code  
    return api.get('/updates/sent.json', {
      start: startTimestamp,
      end: endTimestamp
    });
  },

  saveData: function(data) {
    this._data.add(data.updates);
    return data;
  },
  
  fetch: function(startTimestamp, days) {

    var ranges = this.getRangesForFetch(startTimestamp, days);
    
    if (!ranges.length) {
      return new Promise(function(resolve, reject) {
        resolve(this._data.toJSON());
      }.bind(this));
    }

    return new Promise(function(resolve, reject) {
      var numComplete = 0;

      ranges.forEach(function(range) {

        this.getData(range.start, range.end)
          .then(this.grabDaysForCache.bind(this))
          .then(this.saveData.bind(this))
          .then(function() {
            numComplete++;
            if (numComplete === ranges.length) {
              resolve(this._data.toJSON());
            }
          }.bind(this));

      }.bind(this));

    }.bind(this));
  }
  
};

usage.js

var AnalyticsStore = require('./analyticsStore.js');

var start = Math.round((new Date('2015-05-01T04:00:00.000Z')).valueOf() / 1000);

AnalyticsStore.fetch(start, 14)
  .then(function(updates) {
    // render!!
  });