95.createPubSub

Write a function named createPubSub that returns an object implementing a basic Publish-Subscribe pattern.

The object - let's call it pubSubBroker - should have the following properties:

publish - a method used to publish an event. It should accept 2 parameters:
- eventId - a string uniquely identifying the event
- eventData - any data that should be passed to the subscribers of the event
subscribe - a method used to subscribe to a certain event. It should accept 2 parameters:
- eventId - a string uniquely identifying the event
- callback(data) - a function that will be called when the event is published. The function will receive one parameter - the eventData passed when publishing this specific event.
The function should return another function called unsubscribe that can be used to unsubscribe from this event.

Example 1

class Person {
  name;
  pubSubBroker;
  unsubscribeFn;

  constructor(name, pubSubBroker) {
    this.name = name;
    this.pubSubBroker = pubSubBroker;


    this.unsubscribeFn = this.pubSubBroker.subscribe(
      `calling.${this.name}`,
      (eventData) => {
        this.pickUpPhone(eventData)
      }
    )
  }

  pickUpPhone({ caller }) {
    console.log(`Hello ${caller}, this is ${this.name}! What's up?`);
  }

  callSomeone(name) {
    console.log(`Let's call ${name}.`);
    pubSubBroker.publish(`calling.${name}`, { caller: this.name });
  }

  closePhone() {
    this.unsubscribeFn();
  }
}

const pubSubBroker = createPubSub();
const bob = new Person('Bob', pubSubBroker);
const george = new Person('George', pubSubBroker);
const lisa = new Person('Lisa', pubSubBroker);

bob.callSomeone('Lisa');
/**
 * Should print:
 * > Let's call Lisa.
 * > Hello Bob, this is Lisa! What's up?
 */

george.callSomeone('Lisa');
/**
 * Should print:
 * > Let's call Lisa.
 * > Hello George, this is Lisa! What's up?
 */

lisa.callSomeone('Bob');
/**
 * Should print:
 * > Let's call Bob.
 * > Hello Lisa, this is Bob! What's up?
 */