windowcount.md

windowCount

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

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

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

• windowCount 📰 - Official docs

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