HTMLSelectElement.selectedIndex

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

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。

值

一个数字。

示例

HTML

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

js
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;
});

规范

Specification
HTML Standard
# dom-select-selectedindex-dev

浏览器兼容性

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