EventSignal

EventSignal is a lightweight event messaging controller inspired by js-signals.

Installing

bower

bower install event-signal

npm

npm install event-signal

Examples

function listener(data) {
  console.log(data.message);
}

var resource = {};

// add support for `created` and `updated` events
resource.created = new EventSignal();
resource.updated = new EventSignal();

// add a listener to the `updated` event
resource.updated.addListener(listener);

// emit the `updated` event to all listeners,
// passing an optional `data` object
resource.updated.emit({message: 'foo'});

// remove the listener from the `updated` event-signal
resource.updated.removeListener(listener);

Constructor

var object = {};
object.saved = new EventSignal();

addListener(listener)

Add a listener to the event signal instance.

Returns the EventSignal.

object.saved.addListener(function(){});

// alternatively, use alias `then`
object.saved.then(function(){});

addListener(listener, scope)

Add a listener to the event signal instance, passing an optional scope object that will be this from inside the listener function. If scope is not provided, listener will execute within an anonymous {} scope.

Returns the EventSignal.

var scope = {
  listener: function(){}
};

object.saved.addListener(scope.listener, scope);

addListener(listener, once)

Add a listener to the event signal instance. Passing an optional true for once will automatically remove the listener after one call.

Returns the EventSignal.

object.saved.addListener(function(){}, true);

addListener(listener, scope, once)

The trifecta — add a listener to the event signal instance, passing an optional scope object that will be this from inside the listener function, and optional true for once to automatically remove the listener after one call.

Returns the EventSignal.

var scope = {
  listener: function(){}
};

object.saved.addListener(scope.listener, scope, true);

emit(data)

Emit the signal to all listeners. Optionally pass data to listeners.

Returns the EventSignal.

object.saved.emit();

// examples of passing optional data
object.saved.emit({status: 'success'});
object.saved.emit('foo');

removeListener(listener)

Removes listener and returns self.

Returns the EventSignal.

var listener = function(){};
object.saved.addListener(listener);
object.saved.removeListener(listener);

removeAllListeners()

Removes all registered listeners and returns self.

Returns the EventSignal.

object.saved.removeAllListeners();

listeners()

Returns a cloned array of registered listeners.

object.saved.listeners();
//-> [{callback:function, scope:Object, once:boolean}]

listenerCount();

Returns the number of registered listeners.

object.saved.listenerCount()
//-> number

Naming Conventions

It's recommended that EventSignal instances be named using the past-tense :

• foo.created
• foo.saved
• foo.updated
• foo.ended

are preferred over :

• foo.create
• foo.onSave
• foo.afterUpdate
• foo.ending
• foo.end

Browser Support

• Chrome
• Firefox
• IE 9+
• IE 8 with es5-shim
• Safari

Module Support

• AMD
• CommonJS
• Browser global

License

EventSignal is free to use under the open-source MIT license.