svelte/test/runtime/samples/animation-js/main.html

{#each things as thing (thing.id)}
	<div animate:flip>{thing.name}</div>
{/each}

<script>
	export default {
		animations: {
			flip(node, animation, params) {
				const dx = animation.from.left - animation.to.left;
				const dy = animation.from.top - animation.to.top;

				return {
					duration: 100,
					tick: (t, u) => {
						node.dx = u * dx;
						node.dy = u * dy;
					}
				};
			}
		}
	};
</script>