Emmy

Emmy is an event emitter for lightweight components and jquery plugins. It emits events on any target: plain object, html element, jQuery set, Backbone model, color etc.

Emmy is fully compliant with component-emitter, so you can safely replace it with emmy and vice-versa.

It works both in browser and io. Browserified emmy is only 1.07kb gzipped. Also any method can be required selectively as require('emmy/<method>');, in that you can reduce build size even more.

Last but not least, it is asbestos-free.

Test it, feel it.

Use

For browser use browserify or emmy.js.

Install:

$ npm install emmy

Static methods:

    var Emitter = require('emmy');

    Emitter.on(target, 'evt', function(){});
    Emitter.emit(target, 'evt', data1, data2);
    Emitter.off(target, 'evt');

    //typical use-case
    Emitter.once(webWorker, 'message', function(){...});

Create Emitter instance:

    var Emitter = require('emmy');

    var emitter = new Emitter;
    emitter.emit('something');

Mixin object:

    var Emitter = requre('emmy');

    user = Emitter({name: 'John'});

    user.emit('hello');

Mixin prototype:

    var Emitter = require('emmy');
    Emitter(User.prototype);

Inherit Emitter:

    var Emitter = require('emmy');

    function Actor(){};

    //Give out emmy to an actor :)
    Actor.prototype = Object.create(Emitter);

    var actor = new Actor();

    actor
    //Bind events
    .on('event', handler)
    .on('otherEvent', handler)
    .on('event2', [handler1, handler2]) //bind list of handlers


    //Unbind events
    .off('event', handler)
    .off('otherEvent') //unbind all 'otherEvent' callbacks
    .off('event2', [handler1, handler2]); //unbind list of handlers
    .off(target) //unbind all events


    //Emit events
    .emit('a')
    .emit('b', data, bubbles);

Selective methods:

var once = require('emmy/once');

once(worker, 'message', function(){});

API

Method | Description | --- | --- | --- | on(event, handler) | Register a handler or a list of handlers for an event. one(event, handler) | Register a single-shot event handler or handlers. off(event?, handler?) | Remove an event handler. If no handler passed - remove all registered handlers. In no event passed - remove all registered listeners for all events. emit(event, data?, bubbles?) | Emit an event with params passed. data will be available in event.details, if fired on DOM element. listeners(event)| Get list of listeners for an event hasListeners(event)| Check if emitter has event handlers

Afterword

A somewhat more comprehensive emitter based on emmy - have a look at ENot — event notation system.

There’s also a similar project - emmitt, but it can’t emit bubbling events nor DOM-events at all. It does not provide an Emitter class, listeners methods, and it has a bit too many letters in title :). No, seriously, emmy is only 4 letters length, in that if you have indentation size == 4, your chain calls will look beautiful.