An event aggregator is an application level pub/sub mechanism that allows various pieces of an otherwise segmented and disconnected system to communicate with each other.
Marionette’s EventAggregator is facilitated by Backbone.Wreqr‘s EventAggregator object and Backbone.EventBinder. It combines an EventBinder in to the EventAggregator instance.
Marionette provides an event aggregator with each application instance: MyApp.vent. You can also instantiate your own event aggregator:
js myVent = new Marionette.EventAggregator();
Passing an object literal of options to the constructor function will extend the event aggregator with those options:
js myVent = new Marionette.EventAggregator({foo: "bar"}); myVent.foo // => "bar"
The EventAggregator mixes in an EventBinder object to easily track and unbind all event callbacks, including inline callback functions.
```js vent = new Marionette.EventAggregator();
vent.bindTo(vent, “foo”, function(){ alert(“bar”); });
vent.unbindAll();
vent.trigger(“foo”); // => nothing. all events have been unbound. ```
You can use an event aggregator to communicate between various modules of your application, ensuring correct decoupling while also facilitating functionality that needs more than one of your application’s modules.
```js var vent = new Marionette.EventAggregator();
vent.on(“some:event”, function(){ alert(“Some event was fired!!!!”); });
vent.trigger(“some:event”); ```
For a more detailed discussion and example of using an event aggregator with Backbone applications, see the blog post: References, Routing, and The Event Aggregator: Coordinating Views In Backbone.js.