svelte/documentation/tutorial/09-motion/02-spring/app-b/App.svelte

<script>
	import { spring } from 'svelte/motion';

	let coords = spring(
		{ x: 50, y: 50 },
		{
			stiffness: 0.1,
			damping: 0.25
		}
	);

	let size = spring(10);
</script>

<div style="position: absolute; right: 1em;">
	<label>
		<h3>stiffness ({coords.stiffness})</h3>
		<input bind:value coords.stiffness} type="range" min="0" max="1" step="0.01" />
	</label>

	<label>
		<h3>damping ({coords.damping})</h3>
		<input bind:value coords.damping} type="range" min="0" max="1" step="0.01" />
	</label>
</div>

<svg
	on:mousemove={(e) => coords.set({ x: e.clientX, y: e.clientY })}
	on:mousedown={() => size.set(30)}
	on:mouseup={() => size.set(10)}
>
	<circle cx={$coords.x} cy={$coords.y} r={$size} />
</svg>

<style>
	svg {
		width: 100%;
		height: 100%;
		margin: -8px;
	}
	circle {
		fill: #ff3e00;
	}
</style>