Simple publisher/subscriber design pattern in javascript.

pubsub.js

function PubSub(){
  this.channels = {};
  this.channelBySubscription = {};
  this.nextSubscriptionID = 0;
};

PubSub.prototype.pub = function(channel, publication){
  let currentChannel = this.channels[channel];
  for(let subscriptionID in currentChannel){
    currentChannel[subscriptionID](publication);
  }
};

PubSub.prototype.sub = function(channel, subscriber){
  if(!this.channels[channel]) this.channels[channel] = {};
  let subscriptionID = this.nextSubscriptionID++;
  this.channels[channel][subscriptionID] = subscriber;
  this.channelBySubscription[subscriptionID] = channel;
  return subscriptionID;
};

PubSub.prototype.unsub = function(subscriptionID){
  delete this.channels[this.channelBySubscription[subscriptionID]][subscriptionID];
};

// example
(() => {
  console.log(document.body.innerText);
  pubsub = new PubSub();
  setInterval(() => pubsub.pub('cry', 'wolf!'), 1000);
  let subscription = pubsub.sub('cry', data => console.log(`someone cried ${data}`));
  setTimeout(() => pubsub.unsub(subscription), 5000);
})();