When to use Promise over observable?

Question

Is there any case, where Promise is more powerful as compare to observable? I know a lot of benefits of observables over promises. But Is there any case, I should use only promi

Answer 1

Observable is lazy --> nothing will happen until we subscribed the observable. Observable can be cancelled at anytime by unsubscribing it for memory clean up. Promise can have only one response but observable can have more than one responses.

const promSingle = new Promise(resolve){
  resolve('a');
  resolve('b');
}
promSingle.then(value => {
  console.log(value)
})

Print only a In Observable :

const obSerMult = new Observable(observable){
  Observable.next('a');
  Observable.next('b');
  Observable.next('c');
  Observable.next('d');
}

obSerMult.subscribe(value => {
  console.log(value);
})

print will be a, b , c ,d