Evented.js

function Evented() {
	var events = {};

	this.on = function (name, callback) {
		if (!events[name]) events[name] = [];
		var index = events[name].push(callback);
		return { remove: function () { events[name].splice(index - 1, 1); }
	}

	this.emit = function (name, event) {
		var cbs = events[name];
		if (cbs) cbs.forEach(cb => cb(event));
	}
}
	
class Foo extends Evented {
	bar() {
		this.emit('channel', 'bar was called');
	}
}

x = new Foo();
y = new RetrieveMessages();
const handle = x.on('channel', (channel) => y.goGetMessages(channel))
handle.remove();
	
x = new TwilioClient();
UI.setServer(x)
	
setServer (x) {
	x.on('ready', channel => updateScreen())
	x.on('message', message => addTheMessage(message))
	x.on('close', () => reconnect())
)
// Deferred
	
class StartChannel {
	constructor() {
		this.ready = new Deferred();
		this.findThatChannel();
	}
	
	findThatChannel() { ... }
	
	gotIt() {
		this.ready.resolve(channelName);
	}
}
	
x = new StartChannel();
channel = await x.ready;