messageBus.js

// Make a message bus object for use in your client-side (in-browser) code.
// The name (label) of a message type should be called the topic, in your code. This is standard pub/sub nomenclature.
// The payload is optional.
// Subscribers must be notified in the exact order that they originally subscribed.

// inside component A...
// messageBus.subscribe('new_signup', function(payload) {
//   // do something with the payload
// });

// inside component B...
// messageBus.publish('new_signup', {'foo': 'bar', 'goo': 'gar'} );

const messageBus = {
  topics: {},

  subscribe: function(topic, listener) {
    if (!this.topics[topic]) {
      this.topics[topic] = [];
    }
    console.log(topic);
    this.topics[topic].push(listener);
  },

  publish: function(topic, payload) {
    if (!(this.topics[topic])) {
      return;
    }

    this.topics[topic].forEach(listener => {
      listener(payload !== undefined ? payload : {});
    })
  }
}


// Tests
//inside component A...
messageBus.subscribe('new_signup', function(payload) {
  console.log(payload);
});

// inside component B...
messageBus.publish('new_signup', {'foo': 'bar', 'goo': 'gar'} );