// RxJS v6+
import { interval, of, throwError } from 'rxjs';
import { mergeMap, retry } from 'rxjs/operators';
​
//emit value every 1s
const source = interval(1000);
const example = source.pipe(
  mergeMap(val => {
    //throw error for demonstration
    if (val > 5) {
      return throwError('Error!');
    }
    return of(val);
  }),
  //retry 2 times on error
  retry(2)
);
/*
  output:
  0..1..2..3..4..5..
  0..1..2..3..4..5..
  0..1..2..3..4..5..
  "Error!: Retried 2 times then quit!"
*/
const subscribe = example.subscribe({
  next: val => console.log(val),
  error: val => console.log(`${val}: Retried 2 times then quit!`)
});