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  • Zongshao Che thinks this is interesting:

This method can turn any A+ Promise into an observable.

From

Cover of Mastering Reactive JavaScript

Note

We know Promise starts eagerly. While Observable starts on-demand. Wrapping a Promise to an Observable won't change the behavior of the Promise. [TestCase] const promise = new Promise(resolve => { setTimeout(() => { resolve(1); }, 1000); console.log('promise start'); });

Rx.Observable .fromPromise(promise);