在构建用户界面时，你经常会发现自己处理数据列表。在本练习中，我们重复了多次<button>标记 - 每次更改颜色 - 但仍然需要添加更多内容。
与其费力地复制、粘贴和编辑，我们可以去掉除了第一个按钮之外的所有按钮，然后使用each块
应用程序
<div>
{#each colors as color}
<button
style="background: red"
aria-label="red"
aria-current={selected === 'red'}
onclick={() => selected = 'red'}
></button>
{/each}
</div>表达式（在本例中为
colors）可以是任何可迭代或类似数组的对象 - 换句话说，任何可以与Array.from一起使用的东西。
现在我们需要使用color变量替换"red"
应用程序
<div>
{#each colors as color}
<button
style="background: {color}"
aria-label={color}
aria-current={selected === color}
onclick={() => selected = color}
></button>
{/each}
</div>你可以获取当前的索引作为第二个参数，如下所示
应用程序
<div>
{#each colors as color, i}
<button
style="background: {color}"
aria-label={color}
aria-current={selected === color}
onclick={() => selected = color}
>{i + 1}</button>
{/each}
</div>上一步 下一步
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<script>
const colors = ['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet'];
let selected = $state(colors[0]);
</script>
<h1 style="color: {selected}">Pick a colour</h1><div>
<button
style="background: red"
aria-label="red"
aria-current={selected === 'red'} onclick={() => selected = 'red'}></button>
<button
style="background: orange"
aria-label="orange"
aria-current={selected === 'orange'} onclick={() => selected = 'orange'}></button>
<button
style="background: yellow"
aria-label="yellow"
aria-current={selected === 'yellow'} onclick={() => selected = 'yellow'}></button>
<!-- TODO add the rest of the colours -->
<button></button>
<button></button>
<button></button>
<button></button>
</div>
<style>
h1 {transition: color 0.2s;
}
div {display: grid;
grid-template-columns: repeat(7, 1fr);
grid-gap: 5px;
max-width: 400px;
}
button {aspect-ratio: 1;
border-radius: 50%;
background: var(--color, #fff);
transform: translate(-2px,-2px);
filter: drop-shadow(2px 2px 3px rgba(0,0,0,0.2));
transition: all 0.1s;
}
button[aria-current="true"] {transform: none;
filter: none;
box-shadow: inset 3px 3px 4px rgba(0,0,0,0.2);
}
</style>