from

RxJS 5 from

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/6.2.1/rxjs.umd.js"></script>
<script src="https://rawgit.com/eu81273/jsfiddle-console/master/console.js"></script>

JavaScript

// increment value every 1s, emit even numbers

const evenNumbers = rxjs.Observable.create(observer => {
	let value = 0;
  const interval = setInterval(() => {
  	if(value % 2 === 0) {
    	observer.next(value)
    }
    value++
  }, 1000)
  
  return () => clearInterval(interval)
  
})

const subscribe = evenNumbers.subscribe(val => console.log(val))

setTimeout(() => {
	subscribe.unsubscribe()
}, 10000)