Very basic Pub/Sub

pubsub.mjs

/**
* Very simple Pub/Sub implementation using Symbols and setImmediate.
*/
const topics = {};
const getTokens = (str, obj) => Object.getOwnPropertySymbols(obj).filter(t => t.toString() === `Symbol(${str})`);

export default {
   subscribe: (topic, listener) => {
       const token = Symbol(topic);
       topics[token] = listener;
       return token;
   },
   unsubscribe: token => {
       delete topics[token];
   },
   publish: (topic, data) => {
       getTokens(topic, topics).forEach(token => {
           setImmediate(topics[token], data);
       });
   }
};