Observable toPromise() get all data sent over next()

Question

I have an observable (rxjs) that sends data using subscriber.next(value). How to get these data if the observable is converted to promise via the method toPromise()? Is that even possible? Or is it only possible to get the data passed through the complete method of the observable. Maybe there are options / methods in pipe, before converting to promise to get all data from next() as an array in the data field of the then() method of the promise.

getObservable().toPromise().then(data => {
  // data should contain all data sent from observable.next()
  console.log('Complete: ', data);
}, error => {
  console.log('Error: ', error);
});

• Current behavior (expected but not wanted in this case):
  data contains the data of observable.complete().

• Wanted behavior:
  data contains an array of all observable.next(). This should enabled by an option or pipe.

Example with Observable.range():

let observer = Rx.Observable.range(1,5).toPromise().then(data => {
  console.log('Completed: ', data);
}, error => {
  console.log('Error: ', error);
});

Output:

Completed: 5

Wanted:

Completed: [1, 2, 3, 4, 5]

I'm not sure if this is even possible.

Answer 1

Reduce before you make it a promise

const source = Rx.Observable.of(1, 2, 3, 4);
const example = source.reduce((acc,val) => acc.concat(val), []);

example.toPromise().then((data) => {
    alert(data);
});