Svelte provides a variety of built-in elements. The first, <svelte:self>, allows a component to contain itself recursively.

It's useful for things like this folder tree view, where folders can contain other folders. In Folder.svelte we want to be able to do this...

{#if file.files}
  <Folder {...file}/>
{:else}
  <File {...file}/>
{/if}

...but that's impossible, because a module can't import itself. Instead, we use <svelte:self>:

{#if file.files}
  <svelte:self {...file}/>
{:else}
  <File {...file}/>
{/if}