我们还可以将 bind:value 与 <select> 元素一起使用
应用
<select
bind:value={selected}
onchange={() => answer = ''}
>请注意，<option> 值是对象而不是字符串。Svelte 不介意。
因为我们没有设置
selected的初始值，所以绑定会自动将其设置为默认值（列表中的第一个）。但要小心——在绑定初始化之前，selected保持未定义状态，因此我们不能在模板中盲目地引用例如selected.id。
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<script>
let questions = $state([
{id: 1,
text: `Where did you go to school?`
},
{id: 2,
text: `What is your mother's name?`
},
{id: 3,
text: `What is another personal fact that an attacker could easily find with Google?`
}
]);
let selected = $state();
let answer = $state(''); function handleSubmit(e) {e.preventDefault();
alert(
`answered question ${selected.id} (${selected.text}) with "${answer}"`);
}
</script>
<h2>Insecurity questions</h2>
<form onsubmit={handleSubmit}><select
value={selected} onchange={() => (answer = '')}>
{#each questions as question} <option value={question}> {question.text}</option>
{/each}</select>
<input bind:value={answer} /> <button disabled={!answer} type="submit">Submit
</button>
</form>
<p>
selected question {selected? selected.id
: '[waiting...]'}
</p>