Comment by littlecranky67

Agreed, thats why there are proposals of introducing Observables as ES8 native datatypes. Note that while full RxJS is heavy, Observables are not. Its the multitude of operators to compose observables, and the various helper implementations of Subjects (AsyncSubject, ReplaySubject, BehaviorSubject etc.) - which are similar to Defereds in Promise world - that make RxJS so heavy. If you use only the Observable part with a slim selection of operators in your code, you will not add so much of the library to your code (but granted the patch-based API of RxJS is not really trivial).