publish
Returns a ConnectableObservable, which is a variety of Observable that waits until its connect method is called before it begins emitting items to those Observers that have subscribed to it.
publish<T, R>(selector?: OperatorFunction<T, R>): MonoTypeOperatorFunction<T> | OperatorFunction<T, R>Parameters
Returns
MonoTypeOperatorFunction<T> | OperatorFunction<T, R>: A ConnectableObservable that upon connection causes the source Observable to emit items to its Observers.
Description
Makes a cold Observable hot
Examples
Make source$ hot by applying publish operator, then merge each inner observable into a single one and subscribe.
import { of, zip, interval, merge } from "rxjs";
import { map, publish } from "rxjs/operators";
const source$ = zip(
interval(2000),
of(1, 2, 3, 4, 5, 6, 7, 8, 9),
).pipe(
map(values => values[1])
);
source$.pipe(
publish(multicasted$ => {
return merge(
multicasted$.pipe(tap(x => console.log('Stream 1:', x))),
multicasted$.pipe(tap(x => console.log('Stream 2:', x))),
multicasted$.pipe(tap(x => console.log('Stream 3:', x))),
);
})).subscribe();
/* Results every two seconds
Stream 1: 1
Stream 2: 1
Stream 3: 1
...
Stream 1: 9
Stream 2: 9
Stream 3: 9