svelte/documentation/tutorial/10-transitions/06-transition-events/app-a/App.svelte

<script>
	import { fly } from 'svelte/transition';

	let visible = true;
	let status = 'waiting...';
</script>

<p>status: {status}</p>

<label>
	<input type="checkbox" bind:checked visible} />
	visible
</label>

{#if visible}
	<p transition:fly={{ y: 200, duration: 2000 }}>Flies in and out</p>
{/if}