angular-material-autocomplete-async-part2-component.ts

this.usersForm = this.fb.group({
  userInput: null
})

this.usersForm
  .get('userInput')
  .valueChanges
  .pipe(
    debounceTime(300),
    tap(() => this.isLoading = true),
    switchMap(value => this.appService.search({name: value}, 1)
    .pipe(
      finalize(() => this.isLoading = false),
    )
  )
)
.subscribe(users => this.filteredUsers = users.results);