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---
title: Node.isConnected
slug: Web/API/Node/isConnected
tags:
- API
- DOM
- Node
- Property
- Reference
- 参考
- 属性
translation_of: Web/API/Node/isConnected
---
<div>{{APIRef("DOM")}}</div>
<p><strong><code>isConnected</code></strong> 是 {{domxref("Node")}} 的一个只读属性接口。无论节点是否与 DOM 树连接，该属性都会返回一个{{domxref("Boolean", "布尔值")}}。例如: {{domxref("Document")}} 对象与一般 DOM 树连接，{{domxref("ShadowRoot")}} 与 shadow DOM 连接。</p>
<h2 id="语法">语法</h2>
<pre class="syntaxbox">var <em>isItConnected</em> = <em>nodeObjectInstance</em>.isConnected</pre>
<h3 id="返回值">返回值</h3>
<p>返回 {{domxref("Boolean", "布尔值")}} — 如果该节点与 DOM 树连接则返回 <code>true</code>, 否则返回 <code>false</code>。</p>
<h2 id="样例">样例</h2>
<h3 id="标准_DOM_树">标准 DOM 树</h3>
<pre class="brush: js">let test = document.createElement('p');
console.log(test.isConnected); // Returns false
document.body.appendChild(test);
console.log(test.isConnected); // Returns true
</pre>
<h3 id="Shadow_DOM_树">Shadow DOM 树</h3>
<pre class="brush: js">// Create a shadow root
var shadow = this.attachShadow({mode: 'open'});
// Create some CSS to apply to the shadow dom
var style = document.createElement('style');
console.log(style.isConnected); // returns false
style.textContent = '.wrapper {' +
'position: relative;' +
'}' +
'.info {' +
'font-size: 0.8rem;' +
'width: 200px;' +
'display: inline-block;' +
'border: 1px solid black;' +
'padding: 10px;' +
'background: white;' +
'border-radius: 10px;' +
'opacity: 0;' +
'transition: 0.6s all;' +
'position: absolute;' +
'bottom: 20px;' +
'left: 10px;' +
'z-index: 3;' +
'}' +
// Attach the created style element to the shadow dom
shadow.appendChild(style);
console.log(style.isConnected); // Returns true</pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">规范</th>
<th scope="col">状态</th>
<th scope="col">备注</th>
</tr>
<tr>
<td>{{SpecName('DOM WHATWG','#dom-node-isconnected','isConnected')}}</td>
<td>{{Spec2('DOM WHATWG')}}</td>
<td>Initial definition.</td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
{{Compat("api.Node.isConnected")}}
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