Revision 752373 of UserDataHandler

<p>{{APIRef("DOM")}}</p>

<p>{{obsolete_header(26)}}</p>

<h2 id="Summary">Summary</h2>

<p>When associating user data with a key on a node, <code><a class="internal" href="/En/DOM/Node.setUserData" title="En/DOM/Node.setUserData">Node.setUserData</a>()</code> can also accept, in its third argument, a handler which will be called when the object is cloned, imported, deleted, renamed, or adopted. Per the specification, exceptions should not be thrown in a <code>UserDataHandler</code>. In both <code><a class="internal" href="/en/DOM/document.importNode" title="En/DOM/document.importNode">document.importNode</a>()</code> and <code><a class="internal" href="/En/DOM/Node.cloneNode" title="En/DOM/Node.cloneNode">Node.cloneNode</a>()</code>, although user data is not copied over, the handler will be called.</p>

<h2 id="Properties">Properties</h2>

<p>None.</p>

<h2 id="Methods">Methods</h2>

<p><code>handle (operation, key, data, src, dst)</code> (no return value)</p>

<p>This method is a callback which will be called if a node is being cloned, imported, renamed and as well, if deleted or adopted.</p>

<ul>
 <li><code>operation</code> (unsigned short) is an operation type integer (see below).</li>
 <li><code>key</code> ({{ domxref("DOMString") }}) is the user key.</li>
 <li><code>data</code> ({{ domxref("DOMUserData") }}) is the user data.</li>
 <li><code>src</code> ({{ domxref("Node") }}) is the source node (<code>null</code> if being deleted).</li>
 <li><code>dst</code> ({{ domxref("Node") }}) is the destination node (if any, or <code>null</code>).</li>
</ul>

<h2 id="Constants">Constants</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th>Constant</th>
   <th>Value</th>
   <th>Operation</th>
  </tr>
  <tr>
   <td><code>NODE_CLONED</code></td>
   <td>1</td>
   <td><code><a href="/En/DOM/Node.cloneNode" title="En/DOM/Node.cloneNode">Node.cloneNode</a>()</code></td>
  </tr>
  <tr>
   <td><code>NODE_IMPORTED</code></td>
   <td>2</td>
   <td><code><a href="/en/DOM/document.importNode" title="En/DOM/Document.importNode">Document.importNode</a>()</code></td>
  </tr>
  <tr>
   <td><code>NODE_DELETED</code> {{ unimplemented_inline("550400") }}</td>
   <td>3</td>
   <td>&nbsp;</td>
  </tr>
  <tr>
   <td><code>NODE_RENAMED</code> {{ unimplemented_inline() }}</td>
   <td>4</td>
   <td><code><a href="/En/DOM/Node.renameNode" title="En/DOM/Node.renameNode">Node.renameNode</a>()</code></td>
  </tr>
  <tr>
   <td><code>NODE_ADOPTED</code></td>
   <td>5</td>
   <td><code><a href="/en/DOM/document.adoptNode" title="En/DOM/document.adoptNode">Document.adoptNode</a>()</code></td>
  </tr>
 </tbody>
</table>

<p>(<code>NODE_RENAMED</code> is currently not supported since <code><a href="/En/DOM/Node.renameNode" title="En/DOM/Node.renameNode">Node.renameNode</a>()</code> is not supported.)</p>

<h2 id="Specification">Specification</h2>

<p><a class="external" href="https://www.w3.org/TR/DOM-Level-3-Core/core.html#UserDataHandler">DOM Level 3 Core: UserDataHandler</a></p>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/En/DOM/DOMUserData" title="En/DOM/DOMUserData"><code>DOMUserData</code></a></li>
 <li><a href="/En/DOM/Node.getUserData" title="En/DOM/Node.getUserData"><code>Node.getUserData</code></a>, <a href="/En/DOM/Node.setUserData" title="En/DOM/Node.setUserData"><code>Node.setUserData</code></a></li>
</ul>