Basic Javascript PubSub Pattern

pubsub.js

//events - a super-basic Javascript (publish subscribe) pattern

var events = {
  events: {},
  on: function (eventName, fn) {
    this.events[eventName] = this.events[eventName] || [];
    this.events[eventName].push(fn);
  },
  off: function(eventName, fn) {
    if (this.events[eventName]) {
      for (var i = 0; i < this.events[eventName].length; i++) {
        if (this.events[eventName][i] === fn) {
          this.events[eventName].splice(i, 1);
          break;
        }
      };
    }
  },
  emit: function (eventName, data) {
    if (this.events[eventName]) {
      this.events[eventName].forEach(function(fn) {
        fn(data);
      });
    }
  }
};

My take on the pubsub pattern

// PubSub Pattern

let pubSub = {
  subscribers: new Map(),
  subscribe(name, fn) {
    if(typeof fn !== "function") 
      throw new Error("Second parameter must be a function");
    if(typeof name !== "string") 
      throw new Error("First parameter must be a string");
    
    if (!this.subscribers.has(name)) {
      this.subscribers.set(name, new Map());
    }
    if(fn.name === '') {
      throw new Error('Function cannot be annonymous')
    } else {
      this.subscribers.get(name).set(fn.name, fn)
    }
  },
  unsubscribe(name, fnName) {
    if(this.subscribers.has(name)) {
      if(this.subscribers.get(name).get(fnName)) {
        this.subscribers.get(name).delete(fnName);
        this.subscribers.get(name).size === 0 ? this.subscribers.delete(name) : null;
      } else {
        throw new Error(`Subscriber "${fnName}" not found`);
      }
    } else {
      throw new Error(`Publisher "${name}" not found`)
    }
  },
  publish(name) {
    if(this.subscribers.has(name)) {
      this.subscribers.get(name).forEach(fn => fn());
    } else {
      throw new Error(`Publisher "${name}" not found`)
    }
  }
};

pubSub.subscribe('activate', sayHi = () => {console.log('hi')});
pubSub.subscribe('activate', sayWorld = () => {console.log('world')});
pubSub.subscribe('activate', sayHeizenberg = () => {console.log('Heizenberg')});

pubSub.publish('activate')

Skhmt try events: Object.create( null )

var events = (function() {

    var events = {};

    function on(eventName, fn) {
        events[eventName] = events[eventName] || [];
        events[eventName].push(fn);
    }

    function off(eventName, fn) {
        if (events[eventName]) {
            for (var i = 0; i < events[eventName].length; i++) {
                if( events[eventName][i] === fn ) {
                    events[eventName].splice(i, 1);
                    break;
                }
            }
        }
    }

    function emit(eventName, data) {
        if (events[eventName]) {
            events[eventName].forEach(function(fn) {
                fn(data);
            });
        }
    }

    return {
        on: on,
        off: off,
        emit: emit
    };

})();

That’s iife