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151 lines
13 KiB
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<article id="wikiArticle">
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<div></div>
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<p><code><strong>push()</strong></code> 方法将一个或多个元素添加到数组的末尾，并返回该数组的新长度。</p>
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<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/array-push.html" width="100%"></iframe></div>
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<p class="hidden">The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone <a class="external" href="https://github.com/mdn/interactive-examples" rel="noopener">https://github.com/mdn/interactive-examples</a> and send us a pull request.</p>
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<h2 id="语法">语法</h2>
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<pre><code class="language-javascript">arr.push(element1, ..., elementN)
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</code></pre>
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<h3 id="参数">参数</h3>
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<dl>
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<dt><code>element<em>N</em></code></dt>
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<dd>被添加到数组末尾的元素。</dd>
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</dl>
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<h3 id="返回值" style="line-height: 24px;">返回值</h3>
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<p>当调用该方法时，新的 <a href="Reference/Global_Objects/Array/length" title="length 是Array的实例属性。返回或设置一个数组中的元素个数。该值是一个无符号 32-bit 整数，并且总是大于数组最高项的下标。"><code>length</code></a> 属性值将被返回。</p>
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<h2 id="Description" name="Description" style="margin-bottom: 20px; line-height: 30px;">描述</h2>
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<p>push方法将值追加到数组中。</p>
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<p><code>push</code> 方法有意具有通用性。该方法和 <a href="Reference/Global_Objects/Function/call" title="call() 方法调用一个函数, 其具有一个指定的this值和分别地提供的参数(参数的列表)。"><code>call()</code></a> 或 <a href="Reference/Global_Objects/Function/apply" title="apply() 方法调用一个具有给定this值的函数，以及作为一个数组（或类似数组对象）提供的参数。"><code>apply()</code></a> 一起使用时，可应用在类似数组的对象上。<code>push</code> 方法根据 <code>length</code> 属性来决定从哪里开始插入给定的值。如果 <code>length</code> 不能被转成一个数值，则插入的元素索引为 0，包括 <code>length</code> 不存在时。当 <code>length</code> 不存在时，将会创建它。</p>
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<p>唯一的原生类数组（array-like）对象是 <a href="Reference/Global_Objects/String" title="String 全局对象是一个用于字符串或一个字符序列的构造函数。"><code>Strings</code></a>，尽管如此，它们并不适用该方法，因为字符串是不可改变的。</p>
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<h2 id="示例">示例</h2>
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<h3 id="添加元素到数组">添加元素到数组</h3>
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<p>下面的代码创建了 <code>sports</code> 数组，包含两个元素，然后又把两个元素添加给它。<code>total</code> 变量为数组的新长度值。</p>
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<pre><code class="language-javascript">var sports = ["soccer", "baseball"];
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var total = sports.push("football", "swimming");
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console.log(sports);
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// ["soccer", "baseball", "football", "swimming"]
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console.log(total);
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// 4</code></pre>
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<h3 id="合并两个数组">合并两个数组</h3>
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<p>该示例使用 <a href="Reference/Global_Objects/Function/apply" title="apply() 方法调用一个具有给定this值的函数，以及作为一个数组（或类似数组对象）提供的参数。"><code>apply()</code></a> 添加第二个数组的所有元素。</p>
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<p>注意当第二个数组(如示例中的moreVegs)太大时不要使用这个方法来合并数组，因为事实上一个函数能够接受的参数个数是有限制的。具体可以参考 <a href="Reference/Global_Objects/Function/apply" title="apply() 方法调用一个具有给定this值的函数，以及作为一个数组（或类似数组对象）提供的参数。"><code>apply()</code></a> 。</p>
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<pre><code class="language-javascript">var vegetables = ['parsnip', 'potato'];
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var moreVegs = ['celery', 'beetroot'];
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// 将第二个数组融合进第一个数组
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// 相当于 vegetables.push('celery', 'beetroot');
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Array.prototype.push.apply(vegetables, moreVegs);
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console.log(vegetables);
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// ['parsnip', 'potato', 'celery', 'beetroot']</code></pre>
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<h3 id="像数组一样使用对象">像数组一样使用对象</h3>
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<p>如上所述，push 是特意设计为通用的，我们可以使用它来获得便利。正如下面的例子所示，Array.prototype.push 可以在一个对象上工作。 注意，我们没有创建一个数组来存储对象的集合。 相反，我们将该集合存储在对象本身上，并使用在 Array.prototype.push 上使用的 <code>call</code> 来调用该方法，使其认为我们正在处理数组，而它只是像平常一样运作，这要感谢 JavaScript 允许我们建立任意的执行上下文。</p>
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<pre><code class="language-javascript">var obj = {
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length: 0,
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addElem: function addElem (elem) {
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// obj.length is automatically incremented
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// every time an element is added.
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[].push.call(this, elem);
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}
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};
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// Let's add some empty objects just to illustrate.
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obj.addElem({});
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obj.addElem({});
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console.log(obj.length);
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// → 2</code></pre>
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<p>注意，尽管 obj 不是数组，但是 push 方法成功地使 obj 的 length 属性增长了，就像我们处理一个实际的数组一样。</p>
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<h2 id="规范">规范</h2>
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<table class="standard-table">
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<tbody>
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<tr>
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<th scope="col">Specification</th>
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<th scope="col">Status</th>
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<th scope="col">Comment</th>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,%203rd%20edition,%20December%201999.pdf" hreflang="en" lang="en" rel="noopener" title="ECMAScript 3rd Edition (ECMA-262)">ECMAScript 3rd Edition (ECMA-262)</a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition. Implemented in JavaScript 1.2.</td>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.7" hreflang="en" lang="en" rel="noopener">ECMAScript 5.1 (ECMA-262)<br/><small lang="zh-CN">Array.prototype.push</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td> </td>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.push" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Array.prototype.push</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td> </td>
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</tr>
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<tr>
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<td><a class="external" href="https://tc39.github.io/ecma262/#sec-array.prototype.push" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">Array.prototype.push</small></a></td>
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<td><span class="spec-Draft">Draft</span></td>
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<td> </td>
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</tr>
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</tbody>
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</table>
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<h2 id="浏览器兼容性">浏览器兼容性</h2>
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<div>
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<div>
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<div class="hidden">The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out <a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</div>
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<p></p><div class="bc-data"><a class="bc-github-link external" href="https://github.com/mdn/browser-compat-data" rel="noopener">Update compatibility data on GitHub</a><table class="bc-table bc-table-js"><thead><tr class="bc-platforms"><td></td><th class="bc-platform-desktop" colspan="6"><span>Desktop</span></th><th class="bc-platform-mobile" colspan="7"><span>Mobile</span></th><th class="bc-platform-server" colspan="1"><span>Server</span></th></tr><tr class="bc-browsers"><td></td><th class="bc-browser-chrome"><span class="bc-head-txt-label bc-head-icon-chrome">Chrome</span></th><th class="bc-browser-edge"><span class="bc-head-txt-label bc-head-icon-edge">Edge</span></th><th class="bc-browser-firefox"><span class="bc-head-txt-label bc-head-icon-firefox">Firefox</span></th><th class="bc-browser-ie"><span class="bc-head-txt-label bc-head-icon-ie">Internet Explorer</span></th><th class="bc-browser-opera"><span class="bc-head-txt-label bc-head-icon-opera">Opera</span></th><th class="bc-browser-safari"><span class="bc-head-txt-label bc-head-icon-safari">Safari</span></th><th class="bc-browser-webview_android"><span class="bc-head-txt-label bc-head-icon-webview_android">Android webview</span></th><th class="bc-browser-chrome_android"><span class="bc-head-txt-label bc-head-icon-chrome_android">Chrome for Android</span></th><th class="bc-browser-edge_mobile"><span class="bc-head-txt-label bc-head-icon-edge_mobile">Edge Mobile</span></th><th class="bc-browser-firefox_android"><span class="bc-head-txt-label bc-head-icon-firefox_android">Firefox for Android</span></th><th class="bc-browser-opera_android"><span class="bc-head-txt-label bc-head-icon-opera_android">Opera for Android</span></th><th class="bc-browser-safari_ios"><span class="bc-head-txt-label bc-head-icon-safari_ios">Safari on iOS</span></th><th class="bc-browser-samsunginternet_android"><span class="bc-head-txt-label bc-head-icon-samsunginternet_android">Samsung Internet</span></th><th class="bc-browser-nodejs"><span class="bc-head-txt-label bc-head-icon-nodejs">Node.js</span></th></tr></thead><tbody><tr><th scope="row"><code>push</code></th><td class="bc-supports-yes bc-browser-chrome"><span class="bc-browser-name">Chrome</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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1</td><td class="bc-supports-yes bc-browser-edge"><span class="bc-browser-name">Edge</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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12</td><td class="bc-supports-yes bc-browser-firefox"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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1</td><td class="bc-supports-yes bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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5.5</td><td class="bc-supports-yes bc-browser-opera"><span class="bc-browser-name">Opera</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-safari"><span class="bc-browser-name">Safari</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-webview_android"><span class="bc-browser-name">WebView Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-firefox_android"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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4</td><td class="bc-supports-yes bc-browser-opera_android"><span class="bc-browser-name">Opera Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td><td class="bc-supports-yes bc-browser-nodejs"><span class="bc-browser-name">nodejs</span><abbr class="bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr>
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Yes</td></tr></tbody></table><section class="bc-legend" id="sect1"><h3 class="offscreen" id="Legend">Legend</h3><dl><dt><span class="bc-supports-yes bc-supports">
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<abbr class="bc-level bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr></span></dt><dd>Full support</dd></dl></section></div><p></p>
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</div>
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</div>
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<h2 id="相关链接">相关链接</h2>
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<ul>
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<li><a href="Reference/Global_Objects/Array/pop" title="pop()方法从数组中删除最后一个元素，并返回该元素的值。此方法更改数组的长度。"><code>Array.prototype.pop()</code></a></li>
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<li><a href="Reference/Global_Objects/Array/shift" title="shift() 方法从数组中删除第一个元素，并返回该元素的值。此方法更改数组的长度。"><code>Array.prototype.shift()</code></a></li>
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<li><a href="Reference/Global_Objects/Array/unshift" title="unshift() 方法将一个或多个元素添加到数组的开头，并返回该数组的新长度。"><code>Array.prototype.unshift()</code></a></li>
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<li><a href="Reference/Global_Objects/Array/concat" title="concat() 方法用于合并两个或多个数组。此方法不会更改现有数组，而是返回一个新数组。"><code>Array.prototype.concat()</code></a></li>
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</ul>
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</article> |