Publish and subscribe from https://github.com/marcuswestin/store.js/blob/master/plugins/events.js

PubSub.js

function PubSub() {
	return Object.assign(Object.create(_pubSubBase), {
		_id: 0,
		_subSignals: {},
		_subCallbacks: {}
	})
}

function bind(obj, fn) {
	return function() {
		return fn.apply(obj, Array.prototype.slice.call(arguments, 0))
	}
}

function slice(arr, index) {
	return Array.prototype.slice.call(arr, index || 0)
}

function each(obj, fn) {
	pluck(obj, function(val, key) {
		fn(val, key)
		return false
	})
}

function map(obj, fn) {
	var res = (isList(obj) ? [] : {})
	pluck(obj, function(v, k) {
		res[k] = fn(v, k)
		return false
	})
	return res
}

function pluck(obj, fn) {
	if (isList(obj)) {
		for (var i=0; i<obj.length; i++) {
			if (fn(obj[i], i)) {
				return obj[i]
			}
		}
	} else {
		for (var key in obj) {
			if (obj.hasOwnProperty(key)) {
				if (fn(obj[key], key)) {
					return obj[key]
				}
			}
		}
	}
}

function isList(val) {
	return (val != null && typeof val != 'function' && typeof val.length == 'number')
}

var _pubSubBase = {
	constructor: PubSub,
	_id: null,
	_subCallbacks: null,
	_subSignals: null,
	on: function(signal, callback) {
		if (!this._subCallbacks[signal]) {
			this._subCallbacks[signal] = {}
		}
		this._id += 1
		this._subCallbacks[signal][this._id] = callback
		this._subSignals[this._id] = signal
		return this._id
	},
	off: function(subId) {
		var signal = this._subSignals[subId]
		delete this._subCallbacks[signal][subId]
		delete this._subSignals[subId]
	},
	once: function(signal, callback) {
		var subId = this.on(signal, bind(this, function() {
			callback.apply(this, arguments)
			this.off(subId)
		}))
	},
	fire: function(signal) {
		var args = slice(arguments, 1)
		each(this._subCallbacks[signal], function(callback) {
			callback.apply(this, args)
		})
	}
}