Projects each source value to an Observable which is merged in the output
Observable only if the previous projected Observable has completed.
exhaustMap<T, R, O extends ObservableInput<any>>(project: (value: T, index: number) => O, resultSelector?: (outerValue: T, innerValue: ObservedValueOf<O>, outerIndex: number, innerIndex: number) => R): OperatorFunction<T, ObservedValueOf<O> | R>
Parameters
| project |
A function
that, when applied to an item emitted by the source Observable, returns an
Observable.
|
| resultSelector |
Optional. Default is undefined.
Type: (outerValue: T, innerValue: ObservedValueOf, outerIndex: number, innerIndex: number) => R.
|
Returns
OperatorFunction<T, ObservedValueOf<O> | R>: An Observable containing projected Observables
of each item of the source, ignoring projected Observables that start before
their preceding Observable has completed.
Description
Maps each value to an Observable, then flattens all of
these inner Observables using exhaust.
Returns an Observable that emits items based on applying a function that you
supply to each item emitted by the source Observable, where that function
returns an (so-called "inner") Observable. When it projects a source value to
an Observable, the output Observable begins emitting the items emitted by
that projected Observable. However, exhaustMap ignores every new projected
Observable if the previous projected Observable has not yet completed. Once
that one completes, it will accept and flatten the next projected Observable
and repeat this process.
Example
Run a finite timer for each click, only if there is no currently active timer
import { fromEvent, } from 'rxjs';
import { exhaustMap, take } from 'rxjs/operators';
const clicks = fromEvent(document, 'click');
const result = clicks.pipe(
exhaustMap((ev) => interval(1000).pipe(take(5))),
);
result.subscribe(x => console.log(x));
Overloads
exhaustMap(project: (value: T, index: number) => O): OperatorFunction<T, ObservedValueOf<O>>
Parameters
| project |
Type: (value: T, index: number) => O.
|
Returns
OperatorFunction<T, ObservedValueOf<O>>
|
exhaustMap(project: (value: T, index: number) => O, resultSelector: undefined): OperatorFunction<T, ObservedValueOf<O>>
Parameters
| project |
Type: (value: T, index: number) => O.
|
| resultSelector |
Type: undefined.
|
Returns
OperatorFunction<T, ObservedValueOf<O>>
|
exhaustMap(project: (value: T, index: number) => ObservableInput<I>, resultSelector: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R): OperatorFunction<T, R>
Parameters
| project |
Type: (value: T, index: number) => ObservableInput.
|
| resultSelector |
Type: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R.
|
Returns
OperatorFunction<T, R>
|