HTMLCollection.namedItem()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2015年7月.
HTMLCollection 接口的 namedItem() 方法返回第一个与集合中的 id 或者 name 属性匹配成功的 Element，如果没有匹配成功，则返回 null。
在 JavaScript 中，对一个 String 使用数组括号语法，例如 collection["value"] 等价于 collection.namedItem("value")。
语法
js
const item = collection.namedItem(key);
参数
key是一个字符串，表示我们正在查找元素的id或者name属性。
返回值
item是HTMLCollection第一个与 key 匹配的Element，如果没有，则返回null。
示例
HTML
html
<div id="personal">
<span name="title">Dr.</span>
<span name="firstname">John</span>
<span name="lastname">Doe</span>
<span id="degree">(MD)</span>
</div>
JavaScript
js
const container = document.getElementById("personal");
// Returns the HTMLSpanElement with the name "title" if no such element exists null is returned
const titleSpan = container.children.namedItem("title");
// The following variants return undefined instead of null if there's no element with a matching name or id
const firstnameSpan = container.children["firstname"];
const lastnameSpan = container.children.lastname;
// Returns the span element with the id "degree"
const degreeSpan = container.children.namedItem("degree");
const output = document.createElement("div");
output.textContent = `Result: ${titleSpan.textContent} ${firstnameSpan.textContent} ${lastnameSpan.textContent} ${degreeSpan.textContent}`;
container.insertAdjacentElement("afterend", output);
规范
| Specification |
|---|
| DOM # dom-htmlcollection-nameditem-key |
浏览器兼容性
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