Projects each source value to the same Observable which is merged multiple
times in the output Observable.
mergeMapTo<T, R, O extends ObservableInput<any>>(innerObservable: O, resultSelector?: ((outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R) | number, concurrent: number = Number.POSITIVE_INFINITY): OperatorFunction<T, ObservedValueOf<O> | R>
Parameters
| innerObservable |
An Observable to replace each value from
the source Observable.
|
| resultSelector |
Optional. Default is undefined.
Type: ((outerValue: T, innerValue: ObservedValueOf, outerIndex: number, innerIndex: number) => R) | number.
|
| concurrent |
Optional. Default is Number.POSITIVE_INFINITY.
Maximum number of input
Observables being subscribed to concurrently.
|
Returns
OperatorFunction<T, ObservedValueOf<O> | R>: An Observable that emits items from the given
innerObservable
Description
It's like mergeMap, but maps each value always
to the same inner Observable.
Maps each source value to the given Observable innerObservable regardless
of the source value, and then merges those resulting Observables into one
single Observable, which is the output Observable.
Example
For each click event, start an interval Observable ticking every 1 second
import { fromEvent, interval } from 'rxjs';
import { mergeMapTo } from 'rxjs/operators';
const clicks = fromEvent(document, 'click');
const result = clicks.pipe(mergeMapTo(interval(1000)));
result.subscribe(x => console.log(x));