latestAsync()

Wraps an async function so that only the result of the most recent invocation is delivered. Stale results from earlier calls are discarded and their AbortSignal is fired.

Use cancel() to invalidate all in-flight calls (e.g. on destroy). If onError is omitted, errors from the latest call are silently dropped.

No core dependencies — safe to import from any layer.

Signature

function latestAsync<TInput, TResult>(
	fn: (input: TInput, signal: AbortSignal) => Promise<TResult>,
): {
	/**
	 * Invoke `fn` with `input` and an AbortSignal. If this is the most recent
	 * call when the Promise settles, `onResult` (or `onError`) is called.
	 * Otherwise the result is silently dropped and the signal is aborted.
	 */
	call(input: TInput, onResult: (result: TResult) => void, onError?: (err: unknown) => void): void;
	/** Abort + discard all pending in-flight results. */
	cancel(): void;
}

Parameters

Parameter	Type	Description
fn	(input: TInput, signal: AbortSignal) => Promise<TResult>	The async function to wrap. Receives (input, signal).

Returns

An object with call(input, onResult, onError?) and cancel().

Basic Usage

import { latestAsync } from 'callbag-recharge/raw';

const latest = latestAsync((query: string, signal: AbortSignal) => embed(query));

// Only the result of the last call is delivered; earlier calls are aborted
latest.call('hello', result => console.log(result));
latest.call('world', result => console.log(result)); // 'hello' aborted

// Invalidate all in-flight calls (e.g. on component destroy)
latest.cancel();