This is a draft article likely to evolve or be deleted or merged with another article in the future.
General concepts
Observer
: when subscribing, get all past emitted valuesSubject
: when subscribing, get only next-to-come emitted valuesBehaviorSubject
: likeSubject
but keeps a current state, which is the last received value or the one passed to the constructor if none received, then emits it immediately when being subscribed toReplaySubject
: when subscribing, get all last X emitted valuesAsyncSubject
: emits the result of an asynchronous operation when the observable completes
Misc
shareReplay
: when subscribing, emits the last value. This helps avoid making a new HTTP request for each new subscription, for instance.