--- /dev/null
+import { Observable } from '../Observable';
+import { OperatorFunction } from '../types';
+/**
+ * Branch out the source Observable values as a nested Observable whenever
+ * `windowBoundaries` emits.
+ *
+ * <span class="informal">It's like {@link buffer}, but emits a nested Observable
+ * instead of an array.</span>
+ *
+ * ![](window.png)
+ *
+ * Returns an Observable that emits windows of items it collects from the source
+ * Observable. The output Observable emits connected, non-overlapping
+ * windows. It emits the current window and opens a new one whenever the
+ * Observable `windowBoundaries` emits an item. Because each window is an
+ * Observable, the output is a higher-order Observable.
+ *
+ * ## Example
+ * In every window of 1 second each, emit at most 2 click events
+ * ```ts
+ * import { fromEvent, interval } from 'rxjs';
+ * import { window, mergeAll, map, take } from 'rxjs/operators';
+ *
+ * const clicks = fromEvent(document, 'click');
+ * const sec = interval(1000);
+ * const result = clicks.pipe(
+ * window(sec),
+ * map(win => win.pipe(take(2))), // each window has at most 2 emissions
+ * mergeAll(), // flatten the Observable-of-Observables
+ * );
+ * result.subscribe(x => console.log(x));
+ * ```
+ * @see {@link windowCount}
+ * @see {@link windowTime}
+ * @see {@link windowToggle}
+ * @see {@link windowWhen}
+ * @see {@link buffer}
+ *
+ * @param {Observable<any>} windowBoundaries An Observable that completes the
+ * previous window and starts a new window.
+ * @return {Observable<Observable<T>>} An Observable of windows, which are
+ * Observables emitting values of the source Observable.
+ * @method window
+ * @owner Observable
+ */
+export declare function window<T>(windowBoundaries: Observable<any>): OperatorFunction<T, Observable<T>>;