js手写观察者模式

// 被观察者类
class Subject {
  constructor(name) {
    this.name = name
    this.observers = []
    this.state = 'xx'
  }

  // 被观察者提供订阅观察者方法
  attach(observer){
    this.observers.push(observer)
  }

  // 改变被观察者 调用观察者更新方法
  setState(newState) {
    this.state = newState
    this.observers.forEach(o => o.update(newState))
  }
}

// 观察者类
class Observer {
  constructor(name) {
    this.name = name
  }
  update(newState){
    console.log(`${this.name}say: ${newState}`);
  }
}

const o1 = new Observer('o1')
const o2 = new Observer('o2')

const s = new Subject('s')
s.attach(o1)
s.attach(o2)
s.setState('yyy')