---
title: in: and out:
---

The `in:` and `out:` directives are identical to [`transition:`](transition), except that the resulting transitions are not bidirectional — an `in` transition will continue to 'play' alongside the `out` transition, rather than reversing, if the block is outroed while the transition is in progress. If an out transition is aborted, transitions will restart from scratch.

```svelte
{#if visible}
	<div in:fly out:fade>flies in, fades out</div>
{/if}
```