@reactivex/rxjs/src/add/operator/bufferCount.ts

Reactive Extensions for modern JavaScript

import {Observable} from '../../Observable';
import {bufferCount, BufferCountSignature} from '../../operator/bufferCount';

Observable.prototype.bufferCount = bufferCount;

declare module '../../Observable' {
  interface Observable<T> {
    bufferCount: BufferCountSignature<T>;
  }
}