rx-create.js

import { Observable } from 'rxjs'

const observable = new Observable(observer => {
	const array = [1,2,3,4,5]
	array.forEach(number => {
		if(!isOdd(number)) {
			observer.error('Invalid even number')
		}

		observer.next(number)
	})

	observer.complete()

	return () => cleanUp();
})

observable.subscribe(console.log) // 1, 'Invalid even number'