naive example code for "topic based publish/subscribe model"

pubsub.ts

// naive example code for "topic based publish/subscribe model"
// this is just to illustrate the idea, feature is incomplete, do NOT use in production
// reference: https://github.com/mroderick/PubSubJS

type TopicHandler = (data?: any) => void;

interface ISubscriber {
  topic: string;
  handler: TopicHandler
}

class PubSub {
  static topics: string[] = [];
  static subsribers: Array<ISubscriber> = [];
  static subscribe = (topic: string, handler: TopicHandler) => {
    if (!PubSub.topics.includes(topic)) {
      PubSub.topics.push(topic)
    }
    PubSub.subsribers.push({ topic, handler })
  }
  static publish = (topic: string, data: any) => {
    if (!PubSub.topics.includes(topic)) {
      PubSub.topics = PubSub.topics.concat(topic)
    }
    const topicSubsribers = PubSub.subsribers.filter(it => it.topic === topic)
    topicSubsribers.forEach(it => {
      it.handler(data)
    })
  }
}

let balance: number = 0;

PubSub.subscribe("receive", (dollar: number) => {
  balance += dollar;
  console.log(`Received ${dollar} dollars. Current balance is ${balance}`)
})

PubSub.subscribe("withdraw", (dollar: number) => {
  balance -= dollar;
  console.log(`Withdrawed ${dollar} dollars. Current balance is ${balance}`)
})

PubSub.publish("receive", 100)
PubSub.publish("receive", 50)

setTimeout(() => {
  PubSub.publish("withdraw", 30)
}, 1000);

setTimeout(() => {
  PubSub.publish("withdraw", 40)
}, 2000);