The "Publish-subscribe" pattern

pubsub.js

const pubsub = (function () {
  const topics = {};

  let subUid = -1;

  function publish (topic, args) {
    if (!topics[topic])
      return false;

    const subscribers = topics[topic];

    subscribers.forEach(sub => sub.func(topic, args))

    return this;
  };

  function subscribe (topic, func) {
    if (!topics[topic])
      topics[topic] = [];

    const token = (++subUid).toString();

    topics[topic].push({
      token,
      func
    });

    return token;
  };

  function unsubscribe (token) {
    for (let t in topics) {
      if (topics[t]) {
        for (let i = 0, j = topics[t].length; i < j; i++) {
          if (topics[t][i].token === token) {
            topics[t].splice(i, 1);
            return token;
          }
        }
      }
    }
    return this;
  };

  return {
    publish,
    subscribe,
    unsubscribe
  };
})();