如何在不订阅的情况下使用 Debounce Time

Question

i have a Service witch extends TitleService witch have this method

setTitle(newTitle: string) {
    super.setTitle(newTitle+'TEST');
}

I wanted to set the Title after 2 seconds after the method is called, using debounceTime but i dont want to subscribe to it.

The reason why i need DebounceTime is beacuse if the user trigger the events countles times, then the title would be the last one.

Is there any solution?

Answer 1

You could use a Subject in your CustomTitleService:

import { Injectable } from '@angular/core'
import { Title } from '@angular/platform-browser'
import { Subject } from 'rxjs'
import { debounceTime, startWith } from 'rxjs/operators'

@Injectable({
  providedIn: 'root'
})
export class CustomTitleService {
  titleSubject = new Subject<string>()

  constructor(
    private titleService: Title
  ) {
    this.titleSubject
      .pipe(
        startWith(this.titleService.getTitle()),
        debounceTime(2000) // adjust, here it's 2 sec
      )
      .subscribe(title =>
        this.titleService.setTitle(title)
      )
  }

  setTitle(newTitle: string) {
    this.titleSubject.next(`${newTitle} TEST`)
  }
}

Note that in the official Angular documentation, it is noted that the class Title is final and hence should not be extended. This is why I've maded the CustomTitleService be a wrapper of the Title service instead: https://angular.io/api/platform-browser/Title