Clock.svelte

<script>
	import { onMount } from 'svelte';

	export let time = new Date();
	let hours, minutes, seconds;

	$: {
		// this block runs reactively, whenever
		// `time` changes
		hours = time.getHours();
		minutes = time.getMinutes();
		seconds = time.getSeconds();
	}

	onMount(() => {
		const interval = setInterval(() => {
			time = new Date();
		}, 1000);

		return () => {
			clearInterval(interval);
		};
	});
</script>

<svg viewBox='-50 -50 100 100'>
	<circle class='clock-face' r='48'/>

	<!-- markers -->
	{#each [0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55] as minute}
		<line
			class='major'
			y1='35'
			y2='45'
			transform='rotate({30 * minute})'
		/>

		{#each [1, 2, 3, 4] as offset}
			<line
				class='minor'
				y1='42'
				y2='45'
				transform='rotate({6 * (minute + offset)})'
			/>
		{/each}
	{/each}

	<!-- hour hand -->
	<line
		class='hour'
		y1='2'
		y2='-20'
		transform='rotate({30 * hours + minutes / 2})'
	/>

	<!-- minute hand -->
	<line
		class='minute'
		y1='4'
		y2='-30'
		transform='rotate({6 * minutes + seconds / 10})'
	/>

	<!-- second hand -->
	<g transform='rotate({6 * seconds})'>
		<line class='second' y1='10' y2='-38'/>
		<line class='second-counterweight' y1='10' y2='2'/>
	</g>
</svg>

<style>
	svg {
		width: 100%;
		height: 100%;
	}
	.clock-face {
		stroke: #333;
		fill: white;
	}
	.minor {
		stroke: #999;
		stroke-width: 0.5;
	}
	.major {
		stroke: #333;
		stroke-width: 1;
	}
	.hour {
		stroke: #333;
	}
	.minute {
		stroke: #666;
	}
	.second, .second-counterweight {
		stroke: rgb(180,0,0);
	}
	.second-counterweight {
		stroke-width: 3;
	}
</style>