rxjs-exhaustmap-with-trailing

A variant of RxJS exhaustMap that includes trailing emissions from the source observable.

Just like the exhaustMap() RxJS operator, exhaustMapWithTrailing() will ignore all emissions from source observable as long as the projected observable is pending, but in addition it will include the last emission received from the source observable before the projected observable completed. Think of it as a combination of exhaustMap() and debounce().

Usage

import {exhaustMapWithTrailing} from "rxjs-exhaustmap-with-trailing"
import {delay} from "rxjs/operators"
import {fromEvent, of} from "rxjs"

const clicks = fromEvent(document, "click")

const result = clicks.pipe(
  exhaustMapWithTrailing((value) => of(value).pipe(delay(1000)))
)
result.subscribe((event) =>
  console.log("result: %d, %d", event.clientX, event.clientY)
)

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API

exhaustMapWithTrailing

exhaustMapWithTrailing<T, R>(project: (value: T, index: number) => ObservableInput<R>): OperatorFunction<T, R>;

exhaustMapToWithTrailing

exhaustMapToWithTrailing<T, R>(innerObservable: Observable<R>): OperatorFunction<T, R>;

Credits

This is a packaged and unit tested version of the implementation posted by @aaronjensen here: https://github.com/ReactiveX/rxjs/issues/5004