readyAsync

readyAsync(fn) waits for any tracked async work (promises inside derived / withValue / etc.) to complete before firing. Useful when you need a snapshot of the world after everything has loaded — common in tests or in screenshot / printing flows. For the synchronous form see ready.

A pending async task increments an internal counter; readyAsync callbacks fire only once that counter reaches zero, so several in-flight tasks all settle before the callback runs. If new async work is still outstanding when the queue drains, the callbacks stay queued until everything settles.

Arguments

name	type	description
fn	() => void	function to run once all tracked async work settles

Examples

Snapshot after fetching

Logs only after the tracked fetch inside derived has resolved.

import { derived, readyAsync, render, signal } from 'pota'

function App() {
	const id = signal(1)
	const status = signal('loading…')

	const post = derived(
		() =>
			fetch(
				`https://jsonplaceholder.typicode.com/posts/${id.read()}`,
			),
		res => res.json(),
	)

	readyAsync(() => {
		status.write(`all async settled — post is ${post()?.title}`)
	})

	return (
		<div>
			<p>{status.read}</p>
			<p>{() => post()?.title ?? 'loading…'}</p>
		</div>
	)
}

render(App)