How can I append items to Observable

Question

How do I append items to Observable?

This is some code:

 this.logEntries = this.controllerService.getLog(this.controller.remoteID, this.         


        

Answer 1

Take a look at BehaviorSubject:

It's an Observable where you can push a new item as containing object.

Answer 2

Perhaps the scan operator could interest you. Here is a sample:

obs.startWith([])
 .scan((acc,value) => acc.concat(value))
 .subscribe((data) => {
   console.log(data);
 });

See this question for more details:

• Angular 2 Updating objects in “real time.”

Answer 3

If you want to join two observables together, you need to e.g. combineLatest:

Observable
  .combineLatest(this.logEntries, this.allLogEntries)
  .subscribe(...);

This gives you access to the latest values from each observable, updated as either of them change, and you can combine them as needed.

---

If you want to be able to manually push entries into one of the source observables, make it a Subject:

this.logEntries = new Subject();
Observable
  .combineLatest(this.logEntries, this.allLogEntries)
  .subscribe(...);

then you can invoke an update with:

this.logEntries.next(...);

and your subscription will receive the new logEntries along with the most recent allLogEntries. Depending on the behaviour you want, you can use a ReplaySubject or BehaviourSubject instead of the vanilla Subject.