Get the latest value from Observable without subscribe.

[infacto]

It would be great if we can get the last value from an Observable. Since toPromise is deprecated and the replacements firstValueFrom and lastValueFrom are also not the right one we want. Because firstValueFrom resolves on first value emitted by next. And lastValueFrom requires the Observable to being completed. But in our case we just want the latest received value from Observable. Regardless of any value is received yet or if the Observable is completed or not.

The new feature I suggest is a property or method like getLastValue() which simply returns the latest available value sync (no Promise). The return type is then T | undefined. Undefined if no value received yet (or received undefined). The type is nullish now. But this is ok and expected.

Use case: Get information about the current state of variables which are Observables. When it doesn't matter if any value is emitted or completed.

Or how to achieve this / solve my issue? The function lastValueFrom requires Observable to complete and firstValueFrom returns only the first value. I just want the current (last received value). Currently I have to subscribe to it, take the last, and unsubscribe. Write some ugly code. Any idea is welcome. But what do you think about this suggestion? In my case I have a BehaviorSubject which has an init value and is returned outside as Observable. In this case the strict type is not nullish. But I don't care about. I can handle and expect nullish here. I think it's not the worst idea and is a welcome way to quickly get the current value is a pretty way in this use case.

Or we just extend the method lastValueFrom to get the last value without complete Observable. I want a method what will immediately return a value and not wait for a value / complete and the code never returns. Maybe this will only work with e.g. BehaviorSubject (getValue) because Observable has not value. But I only have access to the Observable. We could find a way... Maybe I have to write my own wrapper.