Pub sub pattern

let subscribers = {};

module.exports = {
    publish(event, data) {
        if (!subscribers[event]) return;

        subscribers.forEach(callback => {
            callback(data);
        })
    },
    subscribe(event, callback) {
        if (!subscribers[event]) {
            subscribers[event] = [];
        }
        subscribers[event].push(callback);
    }
}