How to detect when Angular has attached elements to the DOM?

Question

There is a component:

it\'s component receives a stream of numbers as @Input

Answer 1

this happens in NgInit

https://angular.io/guide/lifecycle-hooks

ngOnInit()
Initialize the directive/component after Angular first displays the data-bound properties and sets the directive/component's input properties.

Called once, after the first ngOnChanges().

Update:

I have propably misunderstood your question. You dont have any update on the ngFor. What is your usecase? Maybe there are different solutions for this.