Describe the bug The every operator can send multiple false's when

`every` operator sending multiple values when re-entrant about rxjs HOT 1 CLOSED

anthonyrota commented on July 29, 2024 1

`every` operator sending multiple values when re-entrant

from rxjs.

Comments (1)

josepot commented on July 29, 2024

This is clearly a bug, the observer should synchronously unsubscribed from the source as soon as it observes a value that doesn't meet the criteria.

If you were using v7, then you could use the following custom implementation which doesn't suffer from this bug:

const customEvery =
  <T>(cb: (value: T, idx: number, source: Observable<T>) => boolean) =>
  (source: Observable<T>): Observable<boolean> =>
    new Observable((observer) => {
      let index = 0;
      const subscriber = new Subscriber<T>({
        next(value: T) {
          if (!cb(value, index++, source)) {
            subscriber.unsubscribe();
            observer.next(false);
            observer.complete();
          }
        },
        error(e: unknown) {
          observer.error(e);
        },
        complete() {
          observer.next(true);
          observer.complete();
        },
      });
      source.subscribe(subscriber);

      return subscriber;
    });

I can't help to wonder what the official way of building a custom operator like that is for v8 🤔

EDIT:

I think that I found it. The new way of doing the equivalent in RxJS 8 would be:

const every =
  <T>(cb: (value: T, idx: number, source: Observable<T>) => boolean) =>
  (source: Observable<T>): Observable<boolean> =>
    new Observable((observer) => {
      let index = 0;
      const subscriber = operate<T, boolean>({
        destination: observer,
        next(value: T) {
          if (!cb(value, index++, source)) {
            subscriber.unsubscribe();
            observer.next(false);
            observer.complete();
          }
        },
        error(e: unknown) {
          observer.error(e);
        },
        complete() {
          observer.next(true);
          observer.complete();
        },
      });
      source.subscribe(subscriber);

      return subscriber;
    });