Change detection with Observable vs Immutable

Question

So I read this article about Angular 2 change detection, but after reading it I have got more confused, so I started reading some of the comments which led to more confusion.

Answer 1

I don't get it how Observables are quite different from Immutables and in this specific case of the Todo app, which approach is better?

Imagine that you have a tree of nodes, and each node has a bit that says "I may have changed". With Observable, we are talking about events getting emitted; the event is dispatched up the tree. In other words:

• Todo_ChangeDetector would be flagged,
• then walking up the tree, Todos_ChangeDetector would be flagged,
• then walking up the tree, App_ChangeDetector would be flagged,
• then the normal change detection kicks in.

Imagine you have 2 todo lists:

1. a grocery list.
2. a list of meetings (work?) for the day.

Which grocery list is active you are currently showing would be the Observable; e.g. a dropdown, nav pills, etc. All the todo items under those 2 lists could be Immutable; e.g. you are not the meeting organizer and cannot change the meetings.