深度复制`BehaviorSubject`中的对象以供将来重置

Question

我的服务中有BehaviorSubject。当服务初始化时，我想把它的副本作为我的功能参考。但每当BehaviorSubject更新副本时，我都会获取更新。怎么预防呢？

这是我的代码：

onlineBookingDatas = new BehaviorSubject(this.onlineBookingDetails);
onlineBookingDatasObserver = this.onlineBookingDatas.asObservable();


    constructor() {

    if(!this.setStaticBookingObject){
      let mark = JSON.stringify(this.onlineBookingDetails);
      this.resetOnlineBookingDetails = JSON.parse(mark); //this copy should not be updated when onlineBookingDatasObserver called. not happening
      this.setStaticBookingObject = true;
      console.log('static', this.resetOnlineBookingDetails ); /updates on call
    }


  }