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---
title: NodeList.prototype.forEach()
slug: Web/API/NodeList/forEach
translation_of: Web/API/NodeList/forEach
---
<p>{{APIRef("DOM")}}</p>
<p>{{domxref("NodeList")}}接口的 <strong><code>forEach()</code></strong> 方法按插入顺序为列表中的每个值对调用一次参数中给定的回调。</p>
<h2 id="语法">语法</h2>
<pre class="syntaxbox"><var>someNodeList</var>.forEach(<var>callback</var>[, <var>thisArg</var>]);
</pre>
<h3 id="参数">参数</h3>
<dl>
<dt><code><var>callback</var></code></dt>
<dd>
<p>为 <code><var>someNodeList</var></code>的每一个元素执行函数。它接受以下三个参数：</p>
<dl>
<dt><code><var>currentValue</var></code></dt>
<dd><code><var>someNodeList</var></code>中的当前元素。</dd>
<dt><code><var>currentIndex</var></code> {{Optional_inline}}</dt>
<dd><code><var>someNodeList</var></code>中的<code><var>currentValue</var></code>所对应的索引值。</dd>
<dt><code><var>listObj</var></code> {{Optional_inline}}</dt>
<dd><code><var>someNodeList</var></code> 在 <code>forEach()</code> 方法中所属的NodeList对象。</dd>
</dl>
</dd>
<dt><code><var>thisArg</var></code> {{Optional_inline}}</dt>
<dd>传递 <code><var>callback</var></code> 的值一般用{{jsxref("this")}}值。</dd>
</dl>
<h3 id="返回值">返回值</h3>
<p>{{jsxref('undefined')}}.</p>
<h2 id="Exceptions">Exceptions</h2>
<p>None.</p>
<h2 id="示例">示例</h2>
<pre class="brush: js;highlight:[6]">let node = document.createElement("div");
let kid1 = document.createElement("p");
let kid2 = document.createTextNode("hey");
let kid3 = document.createElement("span");
node.appendChild(kid1);
node.appendChild(kid2);
node.appendChild(kid3);
let list = node.childNodes;
list.forEach(
function(currentValue, currentIndex, listObj) {
console.log(currentValue + ', ' + currentIndex + ', ' + this);
},
'myThisArg'
);</pre>
<p>上述代码会产生以下结果：</p>
<pre>[object HTMLParagraphElement], 0, myThisArg
[object Text], 1, myThisArg
[object HTMLSpanElement], 2, myThisArg</pre>
<h2 id="Polyfill">Polyfill</h2>
<p>{{Glossary("Polyfill","polyfill")}} 增加了对所有支持<a href="https://caniuse.com/#search=es5">ES5</a>的浏览器的兼容性：</p>
<pre class="brush: js">if (window.NodeList && !NodeList.prototype.forEach) {
NodeList.prototype.forEach = function (callback, thisArg) {
thisArg = thisArg || window;
for (var i = 0; i < this.length; i++) {
callback.call(thisArg, this[i], i, this);
}
};
}</pre>
<p>或者</p>
<pre class="brush: js">if (window.NodeList && !NodeList.prototype.forEach) {
NodeList.prototype.forEach = Array.prototype.forEach;
}</pre>
<p>上面的代码是大部分浏览器实现的 <code>NodeList.prototype.forEach()</code> (例如Chrome).</p>
<h2 id="Specifications">Specifications</h2>
<table class="standard-table">
<thead>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
</thead>
<tbody>
<tr>
<td>{{SpecName("WebIDL", "#es-forEach", "forEach")}}</td>
<td>{{Spec2("WebIDL")}}</td>
<td>Defines <code>forEach</code> on <code>iterable</code> declarations</td>
</tr>
</tbody>
</table>
<h2 id="Browser_Compatibility">Browser Compatibility</h2>
<p>{{Compat("api.NodeList.forEach")}}</p>
<h2 id="See_also">See also</h2>
<ul>
<li>{{domxref("Node")}}</li>
<li>{{domxref("NodeList")}}</li>
</ul>
|
