A minimal PubSub

pubsub.js

(function($) {

  if (!$ || typeof $.extend !== 'function') {
    console.info("No jQuery found. Plugin did not mount.");
    return;
  }

  var _cache = {};

  /**
   * @param  {string} topic
   * @param  {[]} args - An array of arguments passed to subscribers
   */
  function publish(topic, args) {
    (_cache[topic] || []).forEach(function() {
      this.apply($, args || []);
    });
  }

  /**
   * @param  {string}   topic
   * @param  {Function} callback
   * @return {object} A handle representing the subscription
   */
  function subscribe(topic, callback) {
    _cache[topic] = _cache[topic] || [];
    _cache[topic].push(callback);
    return {
      topic: topic,
      callback: callback
    };
  }

  /**
   * @param  {object} sub
   * @param  {string} sub.topic
   * @param  {Function} sub.callback
   */
  function unsubscribe(sub) {
    var foundAt = (_cache[sub.topic] || []).indexOf(sub.callback);
    if (foundAt !== -1) {
      _cache[sub.topic].splice(foundAt, 1);
    } 
  }

  $.extend({
    publish: publish,
    subscribe: subscribe,
    unsubscribe: unsubscribe
  });

}(jQuery));