import { Observable, of } from "rxjs";
// And if I try to return like this
return Observable.of(this.purposes);
I am getting an error stating, Property 'of' does not exist on type 'typeof Observable'
Looks like cartant's comment is correct, the RxJS upgrade guide doesn't cover that method specifically but does say "Classes that operate on observables have been replaced by functions"
Which seems to mean all or most of those class methods like .of, .throw etc. have been replaced by a function
So instead of
import { Observable, of } from "rxjs";
Observable.of(this.purposes);
do
import { of } from "rxjs";
of(this.purposes);