---
title: itemid
slug: Web/HTML/Global_attributes/itemid
tags:
  - Attribute
  - Global attribute
  - HTML
  - Microdata
  - Reference
translation_of: Web/HTML/Global_attributes/itemid
---
<div>{{HTMLSidebar("Global_attributes")}}</div>

<p><code><strong>itemid</strong></code> <a href="/en-US/docs/Web/HTML/Global_attributes">全局属性</a> 是元素的唯一的全局标识符。<code>itemid</code> 属性只能为同时拥有 <strong><code>itemscope</code> </strong>和 <strong><code>itemtype</code></strong> 的元素指定。同时，<code>itemid</code> 只能为拥有 <code>itemscope</code> 的元素指定，它的相应 <code>itemtype</code> 引用或定义了支持全局标识符的词汇。</p>

<p><code>itemtype</code> 的全局标识符的准确含义，由该标识符以指定的词汇提供。词汇定义了全局标识符相同的多个元素是否可以共存，并且如果是这样，这些元素如何处理。 </p>

<p class="note"><strong>注：</strong>Whatwg.org 的定义规定了 <code>itemid</code> 必须是 URL。但是，下面的示例正确展示了 URN 也可以使用。这个不一致性可能反映了 Microdata 规范的不完善性。</p>

<h2 id="示例">示例</h2>

<h3 id="HTML">HTML</h3>

<pre class="brush: html">&lt;dl itemscope
    itemtype="http://vocab.example.net/book"
    itemid="urn:isbn:0-330-34032-8"&gt;
&lt;dt&gt;Title &lt;dd itemprop="title"&gt;The Reality Dysfunction
&lt;dt&gt;Author &lt;dd itemprop="author"&gt;Peter F. Hamilton
&lt;dt&gt;Publication date
&lt;dd&gt;&lt;time itemprop="pubdate" datetime="1996-01-26"&gt;26 January 1996&lt;/time&gt; &lt;/dl&gt;</pre>

<h3 id="结构化数据">结构化数据</h3>

<table class="standard-table">
 <tbody>
  <tr>
   <td colspan="1" rowspan="14">itemscope</td>
   <td>itemtype: itemid</td>
   <td colspan="2" rowspan="1">
    <div class="jyrRxf-eEDwDf jcd3Mb IZ65Hb-hUbt4d">http://vocab.example.net/book: urn:isbn:0-330-34032-8</div>
   </td>
  </tr>
  <tr>
   <td>itemprop</td>
   <td>title</td>
   <td>The Reality Dysfunction</td>
  </tr>
  <tr>
   <td>itemprop</td>
   <td>author</td>
   <td>
    <div class="jyrRxf-eEDwDf jcd3Mb">Peter F. Hamilton</div>
   </td>
  </tr>
  <tr>
   <td>itemprop</td>
   <td>pubdate</td>
   <td>1996-01-26</td>
  </tr>
 </tbody>
</table>

<h3 id="结果">结果</h3>

<p>{{EmbedLiveSample('示例')}}</p>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td><code><a href="https://html.spec.whatwg.org/multipage/microdata.html#attr-itemid">itemid</a></code></td>
   <td> </td>
   <td>WG Note - No longer being actively developed</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>{{CompatibilityTable}}</p>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Chrome for Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="另见">另见</h2>

<ul>
 <li><a href="/en-US/docs/Web/HTML/Global_attributes">其它不同的全局属性</a></li>
 <li>其它 microdata 相关的全局属性
  <ul>
   <li>{{htmlattrxref("itemid")}}</li>
   <li>{{htmlattrxref("itemprop")}}</li>
   <li>{{htmlattrxref("itemref")}}</li>
   <li>{{htmlattrxref("itemscope")}}</li>
   <li>{{htmlattrxref("itemtype")}}</li>
  </ul>
 </li>
</ul>