Svelte Sharing code

在我们目前看到的所有示例中，​<script>​ 块包含在初始化每个组件实例时运行的代码。对于绝大多数组件，这就是您所需要的。

偶尔，您需要在单个组件实例之外运行一些代码。例如，您可以同时播放这五个音频播放器；如果播放一个停止所有其他人会更好。

我们可以通过声明一个 ​<script context="module">​ 块来做到这一点。其中包含的代码将运行一次，即在模块首次计算时，而不是在实例化组件时。将它放在 ​AudioPlayer.svelte​ 的顶部：

<script context="module">
	let current;
</script>

现在组件可以在没有任何状态管理的情况下相互“交谈”：

function stopOthers() {
	if (current && current !== audio) current.pause();
	current = audio;
}

示例代码

• App.svelte

<script>
	import AudioPlayer from './AudioPlayer.svelte';
</script>

<!-- https://musopen.org/music/9862-the-blue-danube-op-314/ -->
<AudioPlayer
	src="https://sveltejs.github.io/assets/music/strauss.mp3" rel="external nofollow" 
	title="The Blue Danube Waltz"
	composer="Johann Strauss"
	performer="European Archive"
/>

<!-- https://musopen.org/music/43775-the-planets-op-32/ -->
<AudioPlayer
	src="https://sveltejs.github.io/assets/music/holst.mp3" rel="external nofollow" 
	title="Mars, the Bringer of War"
	composer="Gustav Holst"
	performer="USAF Heritage of America Band"
/>

<!-- https://musopen.org/music/8010-3-gymnopedies/ -->
<AudioPlayer
	src="https://sveltejs.github.io/assets/music/satie.mp3" rel="external nofollow" 
	title="Gymnopédie no. 1"
	composer="Erik Satie"
	performer="Prodigal Procrastinator"
/>

<!-- https://musopen.org/music/2567-symphony-no-5-in-c-minor-op-67/ -->
<AudioPlayer
	src="https://sveltejs.github.io/assets/music/beethoven.mp3" rel="external nofollow" 
	title="Symphony no. 5 in Cm, Op. 67 - I. Allegro con brio"
	composer="Ludwig van Beethoven"
	performer="European Archive"
/>

<!-- https://musopen.org/music/43683-requiem-in-d-minor-k-626/ -->
<AudioPlayer
	src="https://sveltejs.github.io/assets/music/mozart.mp3" rel="external nofollow" 
	title="Requiem in D minor, K. 626 - III. Sequence - Lacrymosa"
	composer="Wolfgang Amadeus Mozart"
	performer="Markus Staab"
/>

• AudioPlayer.svelte

<script context="module">
	let current;
</script>

<script>
	export let src;
	export let title;
	export let composer;
	export let performer;

	let audio;
	let paused = true;

	function stopOthers() {
		if (current && current !== audio) current.pause();
		current = audio;
	}
</script>

<style>
	article { margin: 0 0 1em 0; max-width: 800px }
	h2, p { margin: 0 0 0.3em 0; }
	audio { width: 100%; margin: 0.5em 0 1em 0; }
	.playing { color: #ff3e00; }
</style>

<article class:playing={!paused}>
	<h2>{title}</h2>
	<p><strong>{composer}</strong> / performed by {performer}</p>

	<audio
		bind:this={audio}
		bind:paused
		on:play={stopOthers}
		controls
		{src}
	></audio>
</article>