How can I subscribe to a different service method using a conditional statement?

Can't figure out how to subscribe to the desired method of an Angular service depending on the conditional statement

  // this.someService.someMethod depending on the conditional statement
  .pipe(takeUntil(this.unsubscribe$))
  .subscribe((items) => {
    this.someData = items;
  });

You could do following, if there might be different services to use:

let source$: Observable<any>;

if ( conditionA ) {
  source$ = this.someService.someMethodA()
} else {
  source$ = this.someService.someMethodB()
}

source$
  .pipe(takeUntil(this.unsubscribe$))
  .subscribe((items) => {
    this.someData = items;
  });

or only saving method name if there is only one service to use. Also it depends on what is more readable to you.

let methodName: string;

if ( conditionA ) {
  methodName = 'someMethodA';
} else {
  methodName = 'someMethodB';
}

this.someService[methodName]()
  .pipe(takeUntil(this.unsubscribe$))
  .subscribe((items) => {
    this.someData = items;
  });