javascript - EventEmitter 的上下文 'this' 未分配给 Observable 类型的 'this' 方法

Question

我查看了 GitHub 存储库中的示例。应用程序成功执行并且编写的代码通常可以正常工作，但我的 Visual Studio Code 中出现以下错误:

The 'this' context of type 'EventEmitter' is not assignable to method's 'this' of type 'Observable'.\n Types of property 'lift' are incompatible.\n Type '(operator: Operator) => Observable' is not assignable to type '(operator: Operator) => Observable'.\n Type 'Observable' is not assignable to type 'Observable'.\n Type 'string' is not assignable to type 'R'.

产生错误的代码如下:

this.notificationService.notifier
.do(message => {
  this.message = message;
  this.snackVisibility = 'visible'; 
})
.switchMap(message => Observable.timer(2000))
.subscribe(timer => this.snackVisibility = 'hidden');

我所有的服务文件代码如下:

import { EventEmitter } from "@angular/core";

export class NotificationService {
   notifier = new EventEmitter<string>();

   notify(message: string) {
      this.notifier.emit(message);
   }
}

尽管该应用程序运行完美，但 VS Code 给出了如图所示的错误:

此错误的最佳解决方案是什么？

Answer 1

服务:

import { Subject } from "rxjs";

export class NotificationService {
   private notifier = new Subject<string>();
   public notifier$ = this.notifier.asObservable();

   notify(message: string) {
      this.notifier.next(message);
   }
}

组件:

this.notificationService.notifier$
.subscribe(message => {
  this.message = message;
  this.snackVisibility = 'visible'; 
  setTimeout(()=>{
   this.snackVisibility = 'hidden';
  }, 2000);
});