Observable vs Promise

Let’s dive right in. We have created something called an Observable. An async construct, much like a promise that we can listen to once the data arrives.

  1. let stream$ = Rx.Observable.from([1,2,3])
  3. stream$.subscribe( (value) => {
  4.    console.log('Value',value);
  5. })
  7. // 1,2,3

The corresponding way of doing this if dealing with promises would be to write

  1. let promise = new Promise((resolve, reject) => {
  2.    setTimeout(()=> {
  3.       resolve( [1,2,3] )
  4.    })
  6. })
  8. promise.then((value) => {
  9.   console.log('Value',data)
  10. })

Promises lack the ability to generate more than one value, ability to retry and it doesn’t really play well with other async concepts.