import {concat, Observable, ReplaySubject, pipe, merge} from 'rxjs';
import {takeUntil, takeWhile, toArray} from 'rxjs/operators';


const rs1 = new ReplaySubject(1);
const rs2 = new ReplaySubject(1);
const rs3 = new ReplaySubject(1);

rs1.next(1);
rs2.next(2);
rs3.next(2);

merge(rs1,rs2,rs3).pipe(toArray()).subscribe(v => {
  console.log({v});
});

{v: [1,2,3]}