Demo:  windowCount

windowCount operator is very similar to bufferCount. Whereas the buffer emits chunks of inputs in arrays, window emits them using separate observables.

windowCount operator emits each chunk as specified by the item count, separately in a new observable.

windowCount(maxItemCount)

//Emits chunks of every 3 items in a new observable
let input = timer(0,1500).pipe(take(7)).pipe(window(3));

//convert the data from the incoming observable into an array
//and emit as the observable completes
let process = mergeMap(v=>v.pipe(toArray()))

let output=input.pipe(process).subscribe(v=>console.log(v))