Angular 4+ ngOnDestroy() in service - destroy observable : <p>In an angular application we have <code>ngOnDestroy()</code> lifecycle hook for a component / directive and we use this hook to unsubscribe the observables.</p>

<p>I want to clear / destory observable that are created in an <code>@injectable()</code> service.
I saw some posts saying that <code>ngOnDestroy()</code> can be used in a service as well.</p>

<p>But, is it a good practice and only way to do so and When will it get called ?
someone please clarify.</p>
