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IObserverPipe

Types​

interface IObserverPipe<GIn, GOut> {
  (emit: IObserver<GOut>): IObserver<GIn>;
}

Definition​

An ObserverPipe receives a value, performs some operation on it, and may emit something else.

Somehow, this is both a push destination (returned Observer), and a push source (received Observer)

note

There is no RxJS equivalent, because there is no subscribe mechanism with an ObserverPipe.

Example​

ObserverPipe that re-emits only distinct received values​

const distinct: IObserverPipe<any, any> = <GValue>(emit: IObserver<GValue>): IObserver<GValue> => {
  let previousValue: GValue;
  return (value: GValue): void => {
    if (value !== previousValue) {
      previousValue = value;
      emit(value);
    }
  };
};

const destination: IObserver<number> = (value: number): void => {
  console.log('value:', value);
}

const emit: IObserver<number> = distinct(destination);

emit(1);
emit(2);
emit(2);
emit(3);

Output:

value: 1
value: 2
value: 3