title: Subscribe is firing when data were not changed in store
body: <p>I have and Angular 5 app with ngrx. I have an array of objects in store. When I subscribe to get this array change event is fired even when I don't change <strong>state.details.selectedOptions.</strong> I changed only <strong>state.details.page</strong> and subscriber was called.</p>
  
  <p>When I change <strong>state.details.selectedOptions</strong> to plain value (string) everything is working as expected. As I see the problem is in arrays/nested elements?</p>
  
  <pre><code>//store
  const initialState = {
    page: null,
    selectedOptions: []
  }
  // selector
  export const selectedOptionsSelector =  createSelector(
    (state: any) =&gt; state.details.selectedOptions
  )
  // also tried such variant
  export const selectedOptionsSelector = (state: any) =&gt; state.details.selectedOptions
  // Component
  ngOnInit() {
    this.store.select(selectedOptionsSelector).subscribe((res: any) =&gt; {
      console.log('selectedOptions', res)
    })
  }
  </code></pre>
  
  <p><strong>Update:</strong></p>
  
  <p>Basically in my case I always have empty array in selectedOptions because initial state didn't change. I tried using distinctUntilChanged in select but it didn't help</p>