@reactivex/rxjs/compat/operator/skipLast.ts

import { Observable } from 'rxjs';
import { skipLast as higherOrder } from 'rxjs/operators';

/**
 * Skip the last `count` values emitted by the source Observable.
 *
 * <img src="./img/skipLast.png" width="100%">
 *
 * `skipLast` returns an Observable that accumulates a queue with a length
 * enough to store the first `count` values. As more values are received,
 * values are taken from the front of the queue and produced on the result
 * sequence. This causes values to be delayed.
 *
 * @example <caption>Skip the last 2 values of an Observable with many values</caption>
 * var many = Rx.Observable.range(1, 5);
 * var skipLastTwo = many.skipLast(2);
 * skipLastTwo.subscribe(x => console.log(x));
 *
 * // Results in:
 * // 1 2 3
 *
 * @see {@link skip}
 * @see {@link skipUntil}
 * @see {@link skipWhile}
 * @see {@link take}
 *
 * @throws {ArgumentOutOfRangeError} When using `skipLast(i)`, it throws
 * ArgumentOutOrRangeError if `i < 0`.
 *
 * @param {number} count Number of elements to skip from the end of the source Observable.
 * @returns {Observable<T>} An Observable that skips the last count values
 * emitted by the source Observable.
 * @method skipLast
 * @owner Observable
 */
export function skipLast<T>(this: Observable<T>, count: number): Observable<T> {
  return higherOrder(count)(this) as Observable<T>;
}