rxjs execute tap only at the first time

Question

I want to execute tap() only when i get the first emitted value

Something like:

Observable
  .pipe(
     tap(() => { /* execute only when I get th         


        

Answer 1

Apart from the already mentioned options you also use multicast.

multicast(new Subject(), s => concat(
  s.pipe(
    take(1),
    tap(v => console.log('tap', v)),
  ),
  s
)

Live demo: https://stackblitz.com/edit/rxjs-shvuxm