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ReplaySubject

"Replays" or emits old values to new subscribers

Examples

Example 1: simple ReplaySubject

// RxJS v6+
import { ReplaySubject } from 'rxjs';
const sub = new ReplaySubject(3);
sub.next(1);
sub.next(2);
sub.subscribe(console.log); // OUTPUT => 1,2
sub.next(3); // OUTPUT => 3
sub.next(4); // OUTPUT => 4
sub.subscribe(console.log); // OUTPUT => 2,3,4 (log of last 3 values from new subscriber)
sub.next(5); // OUTPUT => 5,5 (log from both subscribers)

Additional Resources