js 观察者模式

class Subject {
  constructor() {
    this.observers = [];
  }

  addObserver(observer) {
    this.observers.push(observer);
  }

  removeObserver(observer) {
    const index = this.observers.indexOf(observer);
    if (index !== -1) {
      this.observers.splice(index, 1);
    }
  }

  notify(data) {
    this.observers.forEach(observer => observer.update(data));
  }
}

class Observer {
  constructor(name) {
    this.name = name;
  }

  update(data) {
    console.log(`${this.name} received data: ${data}`);
  }
}

// 使用示例
const subject = new Subject();

const observer1 = new Observer('Observer 1');
const observer2 = new Observer('Observer 2');

subject.addObserver(observer1);
subject.addObserver(observer2);

subject.notify('Hello World!'); // 输出: Observer 1 received data: Hello World! 和 Observer 2 received data: Hello World!

subject.removeObserver(observer1);

subject.notify('Hello Again!'); // 输出: Observer 2 received data: Hello Again!