svelte/test/runtime/samples/transition-js-if-block-in-each-block-bidi-2/main.html

{#each [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] as number}
	{#if foo}
		{#if threshold >= number}
			<div transition:foo>{number}</div>
		{/if}
	{:else}
		{#if threshold >= number}
			<div transition:foo>{number}</div>
		{/if}
	{/if}
{/each}

<script>
	export default {
		transitions: {
			foo: function ( node ) {
				return {
					duration: 100,
					tick: t => {
						node.foo = t;
					}
				};
			}
		}
	};
</script>