windowTime.js

const Observable = require('rxjs/Observable').Observable;
require('rxjs/add/observable/timer');
require('rxjs/add/observable/from');
require('rxjs/add/operator/map');
require('rxjs/add/operator/mergeAll');
require('rxjs/add/operator/windowTime');
const windowTime = require('rxjs/operators').windowTime;
const tap        = require('rxjs/operators').tap;
const mergeAll   = require('rxjs/operators').mergeAll;


const source = Observable.timer(0, 1000);

// All three give same result.

// source.windowTime(3000)
//     .subscribe(subject => {
//         console.log('hello');
//         subject.subscribe(console.log);
//     });

// source.windowTime(3000)
//     .map(r => {
//         console.log('hello');
//         return r;
//     })
//     .mergeAll()
//     .subscribe(console.log);

source.pipe(
    windowTime(3000),
    tap(() => console.log('hello'))
).pipe(mergeAll())
    .subscribe(console.log);

/**
 hello
 0
 1
 2
 hello
 3
 4
 5
 hello
 6
 7
 8
 hello
 9
 **/