heyListen.js

const heyListen = (() => {
	let listeners = {
		once: {},
		on: {}	
	}
	
	const _assignListener = (target, name, listener) => {
		if(target[name]) {
			target[name].push(listener);
		} else {
			target[name] = [listener];
		}
	};
	
	const _executeListeners = (name, type, data) => {
		if(listeners[type][name]) {
			listeners[type][name].forEach((listener) => listener(data));
		}
	}
	
	const getListeners = (name, type) => listeners[type || 'on'][name];
	
	const removeListeners = (name, type) => listeners[type || 'on'][name] = [];
	
	const on = (name, listener) => {
		_assignListener(listeners.on, name, listener);
		
		return () => {
      		listeners.on[name] = listeners.on[name].filter((l) => l !== listener);
    	};
	};
	
	const once = (name, listener) => {
		_assignListener(listeners.once, name, listener);
	};
	
	const emit = (name, data) => {
    	_executeListeners(name, 'on', data);
		_executeListeners(name, 'once', data);
		listeners.once[name] = [];
	};
	
	return { 
		getListeners, 
		removeListeners, 
		on, 
		once, 
		emit 
	};
})();