Angular 8: Have One Variable Subscribe to another variable in 1 Component class

Question

I have two objects in Angular of the same type.

 public addressFinalData: AddressMailingData;
 mailingArchive: AddressMailingData[] = [];

How do I subscribe to data objects of the same type in 1 component

Want mailingArchive[2] to always subscribing to value of addressFinalData (anytime AddressFinalData changes, MailingArchive should store the value in array number 2).

Answer 1

You can create observable of AddressMailingData and in the subscription you can change with new value.

public addressFinalData = new Subject<AddressMailingData>();
 mailingArchive: AddressMailingData[] = [];

ngOnInit() {
   this.addressFinalData.subscribe(
       (val: any) => {
           this.mailingArchive[2] = val;
        }
   )
}

So whenever you are changing the value of addressFinalData, you need to emit that data with next method.

this.addressFinalData.next({newData});