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HTMLSelectElement.selectedIndex 是一个长整型数，它反映了被选中的第一个<option> 元素的索引值。值为-1时表明没有元素被选中。
语法
var index = selectElem.selectedIndex;
selectElem.selectedIndex = index;
实例
HTML
<p id="p">selectedIndex: 0</p> <select id="select"> <option selected>Option A</option> <option>Option B</option> <option>Option C</option> <option>Option D</option> <option>Option E</option> </select>
JavaScript
var selectElem = document.getElementById('select')
var pElem = document.getElementById('p')
// 当有新的<option>元素被选中时
selectElem.addEventListener('change', function() {
var index = selectElem.selectedIndex;
// 把index数据添加到p元素中
pElem.innerHTML = 'selectedIndex: ' + index;
})
Specifications
| Specification | Status | Comment |
|---|---|---|
| HTML Living Standard HTMLSelectElement |
Living Standard | No change since the latest snapshot, HTML5. |
| HTML5 HTMLSelectElement |
Recommendation | Initial definition, snapshot of HTML Living Standard. |
浏览器兼容性
We're converting our compatibility data into a machine-readable JSON format.
This compatibility table still uses the old format,
because we haven't yet converted the data it contains.
Find out how you can help!
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| Basic support | ? | ? | ? | ? | ? |
| Feature | Android | Chrome | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|---|
| Basic support | ? | ? | ? | ? | ? | ? | ? |