---
title: Node
slug: Web/API/Node
tags:
  - API
  - DOM
  - DOM Reference
  - Interface
  - NeedsTranslation
  - Node
  - Reference
  - TopicStub
translation_of: Web/API/Node
---
<div>{{APIRef("DOM")}}</div>

<p><strong><code>Node</code></strong> 是一個被多種 DOM 類型繼承的介面，它讓各種類型的 DOM 都能以同樣的方式來操作。如繼承了相同的方法，或能以相同的方式測試。</p>

<p><code>Node</code> 繼承自 {{domxref("EventTarget")}}，而繼承了 <code>Node</code> 的屬性及方法的介面則有：{{domxref("Document")}}、{{domxref("Element")}}、{{domxref("CharacterData")}}（被 {{domxref("Text")}}、{{domxref("Comment")}} 以及 {{domxref("CDATASection")}} 所繼承）、{{domxref("ProcessingInstruction")}}、{{domxref("DocumentFragment")}}、{{domxref("DocumentType")}}、{{domxref("Notation")}}、{{domxref("Entity")}}、{{domxref("EntityReference")}}。</p>

<p>These interfaces may return null in particular cases where the methods and properties are not relevant. They may throw an exception - for example when adding children to a node type for which no children can exist.</p>

<p>{{InheritanceDiagram}}</p>

<h2 id="屬性">屬性</h2>

<p><em>Inherits properties from its parents {{domxref("EventTarget")}}</em>.<sup>[1]</sup></p>

<dl>
 <dt>{{domxref("Node.baseURI")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("DOMString")}} representing the base URL. The concept of base URL changes from one language to another; in HTML, it corresponds to the protocol, the domain name and the directory structure, that is all until the last <code>'/'</code>.</dd>
 <dt>{{domxref("Node.baseURIObject")}} {{Non-standard_inline()}}</dt>
 <dd>(Not available to web content.) The read-only {{ Interface("nsIURI") }} object representing the base URI for the element.</dd>
 <dt>{{domxref("Node.childNodes")}} {{readonlyInline}}</dt>
 <dd>Returns a live {{domxref("NodeList")}} containing all the children of this node. {{domxref("NodeList")}} being live means that if the children of the <code>Node</code> change, the {{domxref("NodeList")}} object is automatically updated.</dd>
 <dt>{{domxref("Node.firstChild")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("Node")}} representing the first direct child node of the node, or <code>null</code> if the node has no child.</dd>
 <dt>{{domxref("Node.lastChild")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("Node")}} representing the last direct child node of the node, or <code>null</code> if the node has no child.</dd>
 <dt>{{domxref("Node.nextSibling")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("Node")}} representing the next node in the tree, or <code>null</code> if there isn't such node.</dd>
 <dt>{{domxref("Node.nodeName")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("DOMString")}} containing the name of the <code>Node</code>. The structure of the name will differ with the node type. E.g. An {{domxref("HTMLElement")}} will contain the name of the corresponding tag, like <code>'audio'</code> for an {{domxref("HTMLAudioElement")}}, a {{domxref("Text")}} node will have the <code>'#text'</code> string, or a {{domxref("Document")}} node will have the <code>'#document'</code> string.</dd>
 <dt>{{domxref("Node.nodePrincipal")}} {{Non-standard_inline()}}</dt>
 <dd>A {{ Interface("nsIPrincipal") }} representing the node principal.</dd>
 <dt>{{domxref("Node.nodeType")}}{{readonlyInline}}</dt>
 <dd>Returns an <code>unsigned short</code> representing the type of the node. Possible values are:
 <table class="standard-table">
  <tbody>
   <tr>
    <th scope="col">Name</th>
    <th scope="col">Value</th>
   </tr>
   <tr>
    <td><code>ELEMENT_NODE</code></td>
    <td><code>1</code></td>
   </tr>
   <tr>
    <td><code>ATTRIBUTE_NODE</code> {{deprecated_inline()}}</td>
    <td><code>2</code></td>
   </tr>
   <tr>
    <td><code>TEXT_NODE</code></td>
    <td><code>3</code></td>
   </tr>
   <tr>
    <td><code>CDATA_SECTION_NODE</code> {{deprecated_inline()}}</td>
    <td><code>4</code></td>
   </tr>
   <tr>
    <td><code>ENTITY_REFERENCE_NODE</code> {{deprecated_inline()}}</td>
    <td><code>5</code></td>
   </tr>
   <tr>
    <td><code>ENTITY_NODE</code> {{deprecated_inline()}}</td>
    <td><code>6</code></td>
   </tr>
   <tr>
    <td><code>PROCESSING_INSTRUCTION_NODE</code></td>
    <td><code>7</code></td>
   </tr>
   <tr>
    <td><code>COMMENT_NODE</code></td>
    <td><code>8</code></td>
   </tr>
   <tr>
    <td><code>DOCUMENT_NODE</code></td>
    <td><code>9</code></td>
   </tr>
   <tr>
    <td><code>DOCUMENT_TYPE_NODE</code></td>
    <td><code>10</code></td>
   </tr>
   <tr>
    <td><code>DOCUMENT_FRAGMENT_NODE</code></td>
    <td><code>11</code></td>
   </tr>
   <tr>
    <td><code>NOTATION_NODE</code> {{deprecated_inline()}}</td>
    <td><code>12</code></td>
   </tr>
  </tbody>
 </table>
 </dd>
 <dt>{{domxref("Node.nodeValue")}}</dt>
 <dd>Returns / Sets the value of the current node</dd>
 <dt>{{domxref("Node.ownerDocument")}} {{readonlyInline}}</dt>
 <dd>Returns the {{domxref("Document")}} that this node belongs to. If no document is associated with it, returns <code>null</code>.</dd>
 <dt>{{domxref("Node.parentNode")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("Node")}} that is the parent of this node. If there is no such node, like if this node is the top of the tree or if doesn't participate in a tree, this property returns <code>null</code>.</dd>
 <dt>{{domxref("Node.parentElement")}} {{readonlyInline}}</dt>
 <dd>Returns an {{domxref("Element")}} that is the parent of this node. If the node has no parent, or if that parent is not an {{domxref("Element")}}, this property returns <code>null</code>.</dd>
 <dt>{{domxref("Node.previousSibling")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("Node")}} representing the previous node in the tree, or <code>null</code> if there isn't such node.</dd>
 <dt>{{domxref("Node.textContent")}}</dt>
 <dd>Returns / Sets the textual content of an element and all its descendants.</dd>
</dl>

<h3 id="Deprecated_properties">Deprecated properties</h3>

<dl>
 <dt>{{domxref("Node.rootNode")}} {{readOnlyInline}} {{deprecated_inline}}</dt>
 <dd>Returns a {{domxref("Node")}} object representing the topmost node in the tree, or the current node if it's the topmost node in the tree. This has been replaced by {{domxref("Node.getRootNode()")}}.</dd>
</dl>

<h3 id="Obsolete_properties">Obsolete properties</h3>

<dl>
 <dt>{{domxref("Node.localName")}} {{obsolete_inline}}{{readonlyInline}}</dt>
 <dd>Returns a {{domxref("DOMString")}} representing the local part of the qualified name of an element.
 <div class="note">
 <p><strong>Note:</strong> In Firefox 3.5 and earlier, the property upper-cases the local name for HTML elements (but not XHTML elements). In later versions, this does not happen, so the property is in lower case for both HTML and XHTML. {{gecko_minversion_inline("1.9.2")}}</p>
 </div>
 </dd>
 <dt>{{domxref("Node.namespaceURI")}} {{obsolete_inline}}{{readonlyInline}}</dt>
 <dd>The namespace URI of this node, or <code>null</code> if it is no namespace.
 <div class="note">
 <p><strong>Note:</strong> In Firefox 3.5 and earlier, HTML elements are in no namespace. In later versions, HTML elements are in the <code><a class="linkification-ext external" href="https://www.w3.org/1999/xhtml/" title="Linkification: http://www.w3.org/1999/xhtml">https://www.w3.org/1999/xhtml/</a></code> namespace in both HTML and XML trees. {{gecko_minversion_inline("1.9.2")}}</p>
 </div>
 </dd>
 <dt>{{domxref("Node.prefix")}} {{obsolete_inline}}{{readonlyInline}}</dt>
 <dd>Is a {{domxref("DOMString")}} representing the namespace prefix of the node, or <code>null</code> if no prefix is specified.</dd>
</dl>

<h2 id="方法">方法</h2>

<p><em>Inherits methods from its parent, {{domxref("EventTarget")}}</em>.<sup>[1]</sup></p>

<dl>
 <dt>{{domxref("Node.appendChild()")}}</dt>
 <dd>Adds the specified childNode argument as the last child to the current node.<br>
 If the argument referenced an existing node on the DOM tree, the node will be detached from its current position and attached at the new position.</dd>
 <dt>{{domxref("Node.cloneNode()")}}</dt>
 <dd>Clone a {{domxref("Node")}}, and optionally, all of its contents. By default, it clones the content of the node.</dd>
 <dt>{{domxref("Node.compareDocumentPosition()")}}</dt>
 <dd>Compares the position of the current node against another node in any other document.</dd>
 <dt>{{domxref("Node.contains()")}}</dt>
 <dd>Returns a {{jsxref("Boolean")}} value indicating whether a node is a descendant of a given node or not.</dd>
 <dt>{{domxref("Node.getRootNode()")}}</dt>
 <dd>Returns the context object's root which optionally includes the shadow root if it is available.</dd>
 <dt>{{domxref("Node.hasChildNodes()")}}</dt>
 <dd>Returns a {{jsxref("Boolean")}} indicating if the element has any child nodes, or not.</dd>
 <dt>{{domxref("Node.insertBefore()")}}</dt>
 <dd>Inserts a {{domxref("Node")}} before the reference node as a child of the current node.</dd>
 <dt>{{domxref("Node.isDefaultNamespace()")}}</dt>
 <dd>Accepts a namespace URI as an argument and returns a {{jsxref("Boolean")}} with a value of <code>true</code> if the namespace is the default namespace on the given node or <code>false</code> if not.</dd>
 <dt>{{domxref("Node.isEqualNode()")}}</dt>
 <dd>Returns a {{jsxref("Boolean")}} which indicates whether or not two nodes are of the same type and all their defining data points match.</dd>
 <dt>{{domxref("Node.isSameNode()")}}</dt>
 <dd>Returns a {{jsxref("Boolean")}} value indicating whether or not the two nodes are the same (that is, they reference the same object).</dd>
 <dt>{{domxref("Node.lookupPrefix()")}}</dt>
 <dd>Returns a {{domxref("DOMString")}} containing the prefix for a given namespace URI, if present, and <code>null</code> if not. When multiple prefixes are possible, the result is implementation-dependent.</dd>
 <dt>{{domxref("Node.lookupNamespaceURI()")}}</dt>
 <dd>Accepts a prefix and returns the namespace URI associated with it on the given node if found (and <code>null</code> if not). Supplying <code>null</code> for the prefix will return the default namespace.</dd>
 <dt>{{domxref("Node.normalize()")}}</dt>
 <dd>Clean up all the text nodes under this element (merge adjacent, remove empty).</dd>
 <dt>{{domxref("Node.removeChild()")}}</dt>
 <dd>Removes a child node from the current element, which must be a child of the current node.</dd>
 <dt>{{domxref("Node.replaceChild()")}}</dt>
 <dd>Replaces one child {{domxref("Node")}} of the current one with the second one given in parameter.</dd>
</dl>

<h3 id="Obsolete_methods">Obsolete methods</h3>

<dl>
 <dt>{{domxref("Node.getFeature()")}} {{obsolete_inline}}</dt>
 <dd>x</dd>
 <dt>{{domxref("Node.getUserData()")}} {{obsolete_inline}}</dt>
 <dd>Allows a user to get some {{domxref("DOMUserData")}} from the node.</dd>
 <dt>{{domxref("Node.hasAttributes()")}} {{obsolete_inline}}</dt>
 <dd>Returns a {{jsxref("Boolean")}} indicating if the element has any attributes, or not.</dd>
 <dt>{{domxref("Node.isSupported()")}} {{obsolete_inline}}</dt>
 <dd>Returns a {{jsxref("Boolean")}} flag containing the result of a test whether the DOM implementation implements a specific feature and this feature is supported by the specific node.</dd>
 <dt>{{domxref("Node.setUserData()")}} {{obsolete_inline}}</dt>
 <dd>Allows a user to attach, or remove, {{domxref("DOMUserData")}} to the node.</dd>
</dl>

<h2 id="範例">範例</h2>

<h3 id="Browse_all_child_nodes">Browse all child nodes</h3>

<p>The following function recursively cycles all child nodes of a node and executes a callback function upon them (and upon the parent node itself).</p>

<pre class="brush: js">function DOMComb (oParent, oCallback) {
  if (oParent.hasChildNodes()) {
    for (var oNode = oParent.firstChild; oNode; oNode = oNode.nextSibling) {
      DOMComb(oNode, oCallback);
    }
  }
  oCallback.call(oParent);
}</pre>

<h4 id="Syntax">Syntax</h4>

<pre class="syntaxbox">DOMComb(parentNode, callbackFunction);</pre>

<h4 id="Description">Description</h4>

<p>Recursively cycle all child nodes of <code>parentNode</code> and <code>parentNode</code> itself and execute the <code>callbackFunction</code> upon them as <a href="/en-US/docs/JavaScript/Reference/Operators/this" title="en-US/docs/JavaScript/Reference/Operators/this"><code>this</code></a> objects.</p>

<h4 id="Parameters">Parameters</h4>

<dl>
 <dt><code>parentNode</code></dt>
 <dd>The parent node (<code><strong>Node</strong> <a href="/en-US/docs/JavaScript/Reference/Global_Objects/Object" title="en-US/docs/JavaScript/Reference/Global_Objects/Object">Object</a></code>).</dd>
 <dt><code>callbackFunction</code></dt>
 <dd>The callback function (<a href="/en-US/docs/JavaScript/Reference/Global_Objects/Function" title="en-US/docs/JavaScript/Reference/Global_Objects/Function"><code>Function</code></a>).</dd>
</dl>

<h4 id="Sample_usage">Sample usage</h4>

<p>The following example send to the <code>console.log</code> the text content of the body:</p>

<pre class="brush: js">function printContent () {
  if (this.nodeValue) { console.log(this.nodeValue); }
}

onload = function () {
  DOMComb(document.body, printContent);
};</pre>

<h3 id="Remove_all_children_nested_within_a_node">Remove all children nested within a node</h3>

<pre class="brush: js">Element.prototype.removeAll = function () {
  while (this.firstChild) { this.removeChild(this.firstChild); }
  return this;
};</pre>

<h4 id="Sample_usage_2">Sample usage</h4>

<pre class="brush: js">/* ... an alternative to document.body.innerHTML = "" ... */
document.body.removeAll();</pre>

<h2 id="規範">規範</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('DOM WHATWG', '#interface-node', 'Node')}}</td>
   <td>{{Spec2('DOM WHATWG')}}</td>
   <td>Removed the following properties: <code>attributes</code>, <code>namespaceURI</code>, <code>prefix</code>, and <code>localName</code>.<br>
    Removed the following methods: <code>isSupported()</code>, <code>hasAttributes()</code>, <code>getFeature()</code>, <code>setUserData()</code>, and <code>getUserData()</code>.</td>
  </tr>
  <tr>
   <td>{{SpecName('DOM3 Core', 'core.html#ID-1950641247', 'Node')}}</td>
   <td>{{Spec2('DOM3 Core')}}</td>
   <td>The methods <code>insertBefore()</code>, <code>replaceChild()</code>, <code>removeChild()</code>, and <code>appendChild()</code> returns one more kind of error (<code>NOT_SUPPORTED_ERR</code>) if called on a {{domxref("Document")}}.<br>
    The <code>normalize()</code> method has been modified so that {{domxref("Text")}} node can also be normalized if the proper {{domxref("DOMConfiguration")}} flag is set.<br>
    Added the following methods: <code>compareDocumentPosition()</code>, <code>isSameNode()</code>, <code>lookupPrefix()</code>, <code>isDefaultNamespace()</code>, <code>lookupNamespaceURI()</code>, <code>isEqualNode()</code>, <code>getFeature()</code>, <code>setUserData()</code>, and <code>getUserData().</code><br>
    Added the following properties: <code>baseURI</code> and <code>textContent</code>.</td>
  </tr>
  <tr>
   <td>{{SpecName('DOM2 Core', 'core.html#ID-1950641247', 'Node')}}</td>
   <td>{{Spec2('DOM2 Core')}}</td>
   <td>The <code>ownerDocument</code> property was slightly modified so that {{domxref("DocumentFragment")}} also returns <code>null</code>.<br>
    Added the following properties: <code>namespaceURI</code>, <code>prefix</code>, and <code>localName</code>.<br>
    Added the following methods: <code>normalize()</code>, <code>isSupported()</code> and <code>hasAttributes()</code>.</td>
  </tr>
  <tr>
   <td>{{SpecName('DOM1', 'level-one-core.html#ID-1950641247', 'Node')}}</td>
   <td>{{Spec2('DOM1')}}</td>
   <td>Initial definition</td>
  </tr>
 </tbody>
</table>

<h2 id="瀏覽器相容性">瀏覽器相容性</h2>

{{Compat("api.Node")}}