Function: skipUntil()

skipUntil<T, R>(notifier): Operator<T, T>

Defined in: operators/skipUntil.ts:23

Creates a stream operator that skips all values from the source stream until a value is emitted by a notifier stream.

This operator controls the flow of data based on an external signal. It initially drops all values from the source stream. It also subscribes to a separate notifier stream. When the notifier emits its first value, the operator's internal state changes, allowing all subsequent values from the source stream to pass through.

This is useful for delaying the start of a data-intensive process until a specific condition is met, for example, waiting for a user to click a button or for an application to finish loading.

Type Parameters

T

T = any

The type of the values in the source and output streams.

R

R = T

Parameters

notifier

The stream that, upon its first emission, signals that the operator should stop skipping values.

Stream<R> | Promise<R>

Returns

Operator<T, T>

An Operator instance that can be used in a stream's pipe method.

Examples

From skipUntil.spec.ts:4

const emissions = [1, 2, 3, 4, 5];
const source$ = from(emissions);
const notifier$ = createBehaviorSubject(true);
const result: number[] = [];
await new Promise<void>((resolve, reject) => {
  source$.pipe(skipUntil(notifier$)).subscribe({
    next: (val) => result.push(val),
    complete: () => {
      expect(result).toEqual(emissions); // All values should pass through
      resolve();
    },
    error: reject,
  });
});