Autofetch in a Backbone Model/Collection with throttling; autopause if page not in view

backbone-autofetch.js

Collection = Backbone.Collection.extend({

  // ...

  autofetch: function(interval, throttle) {
    var maybeFetch = function() {
      if (! document.hidden) { this.fetch(); }
    }.bind(this);

    this.fetch = _.throttle(this.fetch, throttle * 1000);
    this.fetchId = setInterval(maybeFetch, interval * 1000);
    $(document).on('visibilitychange', maybeFetch);
  }
});

CollectionGetInstance = (function() {
  var instance;

  return function() {
    if (! instance) {
      instance = new Collection();
      instance.promise = instance.fetch();
      instance.autofetch(5, 5);
    }
    return instance;
  };
}());