seitu/dist/core/throttled-fn/index.mjs

import { createReadableSubscription, createSubscription } from "../subscription/index.mjs";
//#region src/core/throttled-fn/index.ts
/**
* Throttled callable that is also a subscribable. First call fires immediately;
* later calls within `wait` batch into one trailing call.
*
* @example
* ```ts twoslash
* import { createThrottledFn } from 'seitu'
*
* const log = createThrottledFn((msg: string) => console.log(msg), 300)
* log.subscribe(result => console.log('result:', result))
* log('hello') // fires immediately
* log('world') // throttled — fires after 300ms
* log.get()
* log.flush()
* ```
*/
function createThrottledFn(fn, wait) {
	let state;
	let timeoutId;
	let trailingArgs;
	const { subscribe, notify } = createSubscription();
	const get = () => state;
	const cancel = () => {
		clearTimeout(timeoutId);
		timeoutId = void 0;
		trailingArgs = void 0;
	};
	const invoke = (args) => {
		state = fn(...args);
		notify();
	};
	const flush = () => {
		const args = trailingArgs;
		cancel();
		if (args) invoke(args);
	};
	return Object.assign((...args) => {
		if (timeoutId) {
			trailingArgs = args;
			return;
		}
		invoke(args);
		timeoutId = setTimeout(flush, wait);
	}, createReadableSubscription(get, subscribe, notify), {
		cancel,
		flush,
		pending: () => trailingArgs !== void 0
	});
}
//#endregion
export { createThrottledFn };