0.0.5 • Public • Published


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What is this?

Just another event-emitter implementation. Nothin' special.


  • Manage custom events in your application easily
  • Listener registration and emitter functionality can be mixed-in to existing objects
  • Listener functions can
    • opt-out of future notification
    • stop continued propagation of an event
    • request event cancellation (like 'preventDefault')

Mmm... Ok. How do I get it?


npm install event-mixer --save


bower install event-mixer --save

What's the Setup?


For node

var eventMixer = require('event-mixer');

In a browser

<script src=".../dist/event-mixer.js"></script>
// or, minified
<script src=".../dist/event-mixer.min.js"></script>

How Does This Work?

You have an object. It needs some pub-sub functionality.

You want it to manage its own event subscriptions.

You want it (or some other object) to manage the event publishing.

var mySubber = {}, myPubber = {};
var mixer = eventMixer.mixer(mySubber, myPubber);

Now mySubber has .on()/.off() methods to register/unregister listener functions, and myPubber has a .fire() method to trigger event notifications.

Now, we need some events

var twist = mixer.create('twist'),
    mangle = mixer.create('mangle'),
    scratch = mixer.create('scratch');

At this point mySubber has .onTwist(), .offTwist(), .onMangle(), etc.

And myPubber now has .fireTwist(), .fireMangle(), etc.

Also, event handlers have been returned. More on those in a sec.

Register some listeners!

mySubber.onTwist([eo => console.log('dog'), eo => console.log('cat')]);
mySubber.onMangle(eo => console.log('mangled!'));
mySubber.on('scratch', eo => console.log('scratched!'));

So we've created events and registered some listeners.

Now we want to fire them. We can use the emitter object,

myPubber.fireTwist();     // => dog => cat
myPubber.fireMangle();    // => mangled!
myPubber.fireScratch();   // => scratched!

or the handlers we got earlier.



Now, let's talk about the event listener functions.


As you likely noticed earlier, listener functions are passed an event object (eo).

  • eo.target
    The target object the mixer was created with.

  • eo.name
    The name of the event that was triggered.

  • eo.data
    Any additional data attached to the event. This will be data used to create the handler merged with any provided when the event was fired. Any changes made by a listener will also be available to subsequent listeners.

The listener object return value has some flags you can use.

If the listener wants to opt out of future event notifications:

return { remove: true };

If the listener wants to be the last one called for this event:

return { stop: true };

If the listener wants to stop whatever happens next (like .preventDefault()):

return { prevent: true };

Use whatever combination of these flags you like:

return { prevent: true, remove: true, stop: false };

Beyond this, listener return values are ignored.

Nice. Can I Get an API Quick-Ref?

Yep. Here you go!


  • mixer(target:object, emitter:object):mixer
    Returns an event manager object that mixes listener registration methods into target object and event trigger methods into emitter object. Both arguments are optional.

  • handler(target:object, name:string, data:object):handler
    Returns an event handler object that passes triggered events on to its listeners. Data provided here will be passed to each listener. (Note: Listeners are not managed as a Set so a handler can add the same listener function multiple times.)


  • create(name:string, data:object):handler
    Creates a new event handler. This adds on/off methods to target object and a fire method to emitter object.

  • destroy(name:string):handler
    Destroys an event handler. This removes on/off methods from target object and the fire method from emitter object.

  • emitter():object
    Returns the emitter for this mixer.

  • event(name:string):handler
    Returns the named handler object.

  • fire(name:string, data:object):boolean
    Fires the named event. This method is also added directly to the emitter object.

  • has(name:string):boolean
    Returns true if there is an event handler for the given name.

  • names():array
    Returns the names of all event handlers.

  • off(name:string|array, listener:function|array):this
    Removes listener(s) from named event(s). This method is also added directly to the target object.

  • on(name:string|array, listener:function|array):this
    Adds listener(s) to named event(s). This method is also added directly to the target object.

  • target():object
    Returns the target of this mixer.


  • add(listener:function|array):this
    Alias for .append().

  • append(listener:function|array):this
    Appends listener function(s) to end of listener list.

  • at(index:number):listener
    Returns the listener at the given index or null if not found.

  • clear():this
    Removes all listeners.

  • count():number
    Returns the number of listeners in this event handler.

  • cut(index:number):listener
    Removes and returns the listener at the given index or null if not found.

  • each(callback:function):this
    Filters the listener array. Each listener (and its index) is passed to 'callback' and replaced by its return value. If the callback does not return a function the listener will be omitted.

  • fire(data:object):boolean
    Triggers the event (with optional data). The returned boolean value indicates if the event should continue normally (true) or not (false).

  • has(listener:function):boolean
    Returns true if this handler has the given listener function.

  • indexOf(listener:function, start:number):number
    Returns the index of given listener in the listener list or -1 if not found. Specify 'start' to begin the search at a specific index.

  • prepend(listener:function|array):this
    Prepends listener function(s) to beginning of listener list.

  • remove(listener:function|array):this
    Removes listener function(s).


  • off(name:string|array, listener:function|array):this
    Removes listener(s) from named event handler(s). Added from mixer.

  • on(name:string|array, listener:function|array):this
    Adds listener(s) to named event handler(s). Added from mixer.

  • offXxx(listener:function|array):this
    Removes listener(s) from event handler 'Xxx'. Added via mixer.create().

  • onXxx(listener:function|array):this
    Adds listener(s) to event handler 'Xxx'. Added via mixer.create().


  • fire(name:string, data:object):boolean
    Fires the named event. Added from mixer.

  • fireXxx(data:object):boolean
    Fires the event named 'Xxx'. Added via mixer.create().

Anything Else I Should Know?


{ distrib } { updates } { feedback } { license } { versioning }

Please be sure to check 'updates' link when upgrading to a new version.


EventMixer uses Jasmine for testing and Istanbul for coverage analysis.

npm test

Codeship Status for captison/event-mixer


Don't Get Triggered! Happy Eventing!

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