Javascript 角度4-观察变量的变化特性

我想查看json的嵌套属性。每当此嵌套属性发生更改时，调用fn（）

Fn更改值

public changeUser(item) {
    this.user.selected = item;
    /*Some Code here*/
}

  public customLogin(user) {
        /*Some Code here*/
        this.user.selected = user;
        /*Some Code here*/
}

每当

此.user.selected的值更改时，调用函数。
我也在使用
rxjx

有什么建议吗
 您可以这样做：

export class HeaderComponent implements OnDestroy {
  user: any;
  userSelectSubject: BehaviorSubject<{name: string, img: string}>;
  private userSelectSubscription: Subscription;

  constructor(){
    this.user = {
      options: [
        { name: 'Jenny Hess', img: 'assets/img/avatar/small/jenny.jpg' },
        { name: 'Elliot Fu', img: 'assets/img/avatar/small/elliot.jpg' },
        { name: 'Stevie Feliciano', img: 'assets/img/avatar/small/stevie.jpg' }
      ]
    }

    this.userSelectSubject = new BehaviorSubject<{name: string, img: string}>({ name: 'Jenny Hess', img: 'assets/img/avatar/small/jenny.jpg' });

    this.userSelectSubscription = this.userSelectSubject.subscribe((newSelectedUser) => {
      this.user.selected = newSelectedUser;
    });
  }

  ngOnDestroy() {
    this.userSelectSubscription.unsubscribe();
  }
}

导出类标题组件实现OnDestroy{
用户：任何；
用户选择主题：行为主题；
private userSelectSubscription:Subscription；
构造函数（）{
此用户={
选项：[
{name:'Jenny Hess'，img:'assets/img/avatar/small/Jenny.jpg'}，
{name:'Elliot Fu'，img:'assets/img/avatar/small/Elliot.jpg'}，
{name:'Stevie Feliciano'，img:'assets/img/avatar/small/Stevie.jpg'}
]
}
this.userSelectSubject=newbehaviorsubject（{name:'Jenny Hess'，img:'assets/img/avatar/small/Jenny.jpg'}）；
this.userSelectSubscription=this.userSelectSubject.subscripte（（newSelectedUser）=>{
this.user.selected=newSelectedUser；
});
}
恩贡德斯特罗（）{
此.userSelectSubscription.unsubscribe（）；
}
}

然后只需调用
this.userSelectSubject.next（{…}）
将新选择的用户作为参数传递。
是
HeaderComponent
需要查看值或其他组件（父组件）？@肾上腺素DJ编号
此用户的值。所选
通过函数在
HeaderComponent
中更改。提供更多信息，说明将以何种方式更改。您可以尝试使用
ngDoCheck
。提供详细信息，如：如何准确更改属性，您希望在何处观察该更改？@dee zg@YordanNikolov编辑了添加
Fn更改值的帖子
谢谢@giovain It Helped导入订阅，但出现错误。“订阅不是一个函数”，我错过了什么。？
export class HeaderComponent implements OnDestroy {
  user: any;
  userSelectSubject: BehaviorSubject<{name: string, img: string}>;
  private userSelectSubscription: Subscription;

  constructor(){
    this.user = {
      options: [
        { name: 'Jenny Hess', img: 'assets/img/avatar/small/jenny.jpg' },
        { name: 'Elliot Fu', img: 'assets/img/avatar/small/elliot.jpg' },
        { name: 'Stevie Feliciano', img: 'assets/img/avatar/small/stevie.jpg' }
      ]
    }

    this.userSelectSubject = new BehaviorSubject<{name: string, img: string}>({ name: 'Jenny Hess', img: 'assets/img/avatar/small/jenny.jpg' });

    this.userSelectSubscription = this.userSelectSubject.subscribe((newSelectedUser) => {
      this.user.selected = newSelectedUser;
    });
  }

  ngOnDestroy() {
    this.userSelectSubscription.unsubscribe();
  }
}