Publish/Subscribe Snippet 2023

pubsub.js

const PubSub = (() => {
  const topics = {};
  const hOP = topics.hasOwnProperty;

  return {
    subscribe(topic, listener) {
      // Create the topic's object if not yet created
      if(!hOP.call(topics, topic)) topics[topic] = [];

      // Add the listener to queue
      let index = topics[topic].push(listener) -1;

      // Provide handle back for removal of topic
      return {
        remove() {
          delete topics[topic][index];
        }
      };
    },
    publish(topic, info) {
      // If the topic doesn't exist,
      // or there's no listeners in queue,
      // just leave
      if(!hOP.call(topics, topic)){ return; }

      // Cycle through topics queue, fire!
      topics[topic].forEach(item => {
        item(info != undefined ? info : {});
      });
    }
  };
})();