windowCount

signature: windowCount(windowSize: number, startWindowEvery: number): Observable

Observable of values from source, emitted each time provided count is fulfilled.

Ultimate RxJS

Examples

Example 1: Start new window every x items emitted

( StackBlitz | jsBin | jsFiddle )

// RxJS v6+
import { interval } from 'rxjs';
import { windowCount, mergeAll, tap } from 'rxjs/operators';
//emit every 1s
const source = interval(1000);
const example = source.pipe(
//start new window every 4 emitted values
windowCount(4),
tap(_ => console.log('NEW WINDOW!'))
);
const subscribeTwo = example
.pipe(
//window emits nested observable
mergeAll()
/*
output:
"NEW WINDOW!"
0
1
2
3
"NEW WINDOW!"
4
5
6
7
*/
)
.subscribe(val => console.log(val));

Additional Resources

📁 Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/windowCount.ts