angular losing data on refresh code example

Example: refresh data after some time angular

import { Subscription, timer } from 'rxjs';
import { switchMap } from 'rxjs/operators';

subscription: Subscription;
statusText: string;

ngOnInit() {
    this.subscription = timer(0, 10000).pipe(
      switchMap(() => this.myservice.checkdata())
    ).subscribe(result => this.statustext = result);
}

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