Is it possible that sending a "message" may not be received if only the option complete is used?
The complete
handler should not be used to receive messages sent through an Observable. Its purpose is to respond when the Observable is marked as complete. Here's an example of how it should be utilized:
this.someService.getMessage().subscribe({
next: message => console.log(message);
error: err => console.error('Observer encountered an error: ' + err),
complete: () => console.log('Observer was closed'),
});
In the scenario where the Observable emits a message ("hello") before being completed, you would observe:
hello
Observer was closed
Additionally, there is an important point to note:
Delayed values can still be processed by the next handler after completion.
This indicates that occasionally, the Observable might be marked as complete prior to receiving the final message. This situation could appear like this:
Observer was closed
hello
This outcome may be unexpected, which is why it's emphasized in the documentation so that developers are aware and can handle such cases accordingly.
If the next
handler is omitted like below:
this.someService.getMessage().subscribe({
error: err => console.error('Observer encountered an error: ' + err),
complete: () => console.log('Observer was closed'),
});
... then regardless of the number of messages received from the subscription, you will simply see:
Observer was closed