Angular/RxJs When should I unsubscribe from `Subscription`

Question

When should I store the Subscription instances and invoke unsubscribe() during the NgOnDestroy life cycle and when can I simply ignore them?

Answer 1

Angular 2 official documentation provides an explanation for when to unsubscribe and when it can be safely ignored. Have a look at this link:

https://angular.io/docs/ts/latest/cookbook/component-communication.html#!#bidirectional-service

Look for the paragraph with the heading Parent and children communicate via a service and then the blue box:

Notice that we capture the subscription and unsubscribe when the AstronautComponent is destroyed. This is a memory-leak guard step. There is no actual risk in this app because the lifetime of a AstronautComponent is the same as the lifetime of the app itself. That would not always be true in a more complex application.

We do not add this guard to the MissionControlComponent because, as the parent, it controls the lifetime of the MissionService.

I hope this helps you.