Do I need to unsubscribe from subscribe in Angular

Question

In an Angular service I have a function, that executes on certain events. Inside the callback I need to fetch some data from ngrx store and do something with it based on a condition. Here is a simplified example:

export class MyService {

  constructor(private store: Store<{}>) {

    Library.onSomethingChanged((val) => {
      this.store.select(mySelector).pipe(
        tap((valueFromStore) => {
          if (valueFromStore) {
            // do something
          }
        })
      ).subscribe()
    })

  }

}

I'm not quite sure how to deal with subscribe in this situation. I only need the pipe to execute once if something changes. Would this create a new subscription every time the onSomethingChanged callback executes?

Answer 1

I think if you use take(1) you will get the first emission and the subscription will not leak:

  Library.onSomethingChanged((val) => {
  this.store.select(mySelector).pipe(
    take(1),
    tap((valueFromStore) => {
      if (valueFromStore) {
        // do something
      }
    })
  ).subscribe()