title: Should I instantiate an Observable from the constructor() or ngOnInit()?
body: <p>I know in general, one should instantiate instance variables and dependencies in the constructor, whether it is injected, <code>new</code>'ed up, or from a <code>@ngrx/store</code> <code>select()</code>:</p>
  
  <pre><code>@Component
  export class MyCoolComponent implements OnInit {
      public coolObservable$: Observable&lt;any&gt;;
      public myItems$: Observable&lt;Item[]&gt;;
  
      constructor(private myCoolService: CoolService, private store: Store) {
          // Instantiate the Observables here?
          this.coolObservable$ = Observable.of('cool!');
          this.myItems$ = this.store.select('items');
      }
  
      public ngOnInit() {
          // Or instantiate the Observables here?
          this.coolObservable$ = Observable.of('cool!');
          this.myItems$ = this.store.select('items'); 
      }
  }
  </code></pre>
  
  <p>What is the best practice in <code>Angular</code>?</p>