题解 | #观察者模式#

            class Observerd {
                constructor(name){
                    this.name = name;
                    this.state = "打游戏";
                    this.observerSet = new Set()
                }

                setObserver(observer) {
                    this.observerSet.add(observer)
                }

                setState(state) {
                    this.state = state
                    for(let observer of this.observerSet){
                        observer.update(this.name,state)
                    }
                }
            }

            class Observer{
                update(name,state){
                    console.log(`${name}正在${state}`)
                }
            }