Backbone.Attributes

Backbone.Attributes is a tiny (~400 bytes minified/gz) plugin to give any object Backbone.Model getter/setter methods. Sometimes models are too heavyweight or you don't need the full sync / collection methods Backbone Models provide.

var view = new Backbone.View;
_.defaults(view, Backbone.Attributes);

view.on('change:title', function(title) {
  this.$('.title').text(title);
});

view.set('title', 'Results');

These methods are borrowed from Backbone.Model, so their functionality is exactly the same. You can pass a hash of properties, listen on multiple change events, or trigger complex change sequences.

Note: get and set collide with native Collection#get and Collection#set. If your target is a Collection, you must use the getAttribute/setAttribute aliases instead.

The target object's attributes property is set on the first call to a method that relies on its existence (clear, get or set). This is mostly to ensure that attributes aren't shared between instances. If you need attributes earlier, you may create it yourself (e.g. during initalize) and Backbone.Attributes will respect the existing values.

Example

Let's say we're building a music player application that has a list of tracks organized into a Playlist collection. When the user clicks on the "next" button, we want to update the index of the currently playing track and alert any views listening on the Playlist. It might look something like this:

var Playlist = Backbone.Collection.extend({
  defaults: {
    currentTrack: 0,
    title: "My Playlist"
  },
  initialize: function() {
    this.on('change:currentTrack', function() {
      var oldTrack = this.at(this.previous('currentTrack')),
          newTrack = this.at(this.getAttribute('currentTrack'));

      this.stopListening(oldTrack, 'track:done');
      this.listenTo(newTrack, 'track:done', this.nextTrack);
    });
  },
  setTrack: function(trackPosition) {
    this.setAttribute('currentTrack', trackPosition);
  },
  nextTrack: function() {
    this.setTrack(this.getAttribute('currentTrack') + 1);
  }
});

_.defaults(Playlist.prototype, Backbone.Attributes);

var PlayerView = Backbone.View.extend({
  events: {
    'click .track': 'setTrack'
  },
  initialize: function() {
    this.listenTo(this.collection, 'change:currentTrack', this.updateTrackDetails);
  },
  setTrack: function(e) {
    this.collection.setTrack($(e.target).index());
  },
  updateTrackDetails: function() {
    // Set album art, etc.
  }
});

new PlayerView({collection: new Playlist});