path: root/files/ja/xpcomutils.jsm/index.html

---
title: XPCOMUtils.jsm
slug: XPCOMUtils.jsm
tags:
  - NeedsContent
  - 'XPCOM:Language Bindings'
  - XPConnect
translation_of: Mozilla/JavaScript_code_modules/XPCOMUtils.jsm
---
<p><code>XPCOMUtils.jsm</code> は JS コンポーネントローダによって読み込まれる JavaScript コンポーネントのためのユーティリティを含んだモジュールです。</p>

<p>
 </p><p>To use this, you first need to import the code module into your JavaScript scope:</p>
<p></p>

<pre class="line-numbers  language-html"><code class="language-html">Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");</code></pre>

<h2 id="Using_XPCOMUtils">Using XPCOMUtils</h2>

<p>Exposing a JavaScript class as a component using these utility methods requires four key steps:</p>

<ol>
 <li>Import <code>XPCOMUtils.jsm</code>, as explained previously.</li>
 <li>Declare the class (or multiple classes) implementing the component(s).</li>
 <li>Create an array of component constructors.</li>
 <li>Define the <code>NSGetFactory()</code> or <code>NSGetModule()</code> entry point.</li>
</ol>

<h3 id="Pseudocode">Pseudocode</h3>

<p>This section provides some pseudocode that demonstrates how to put together a JavaScript class based on the steps listed above.</p>

<h4 id="Constructor">Constructor</h4>

<p>The constructor is a simple method that handles any required initialization tasks.</p>

<pre class="brush: js line-numbers  language-js"><code class="language-js"><span class="keyword token">function</span> <span class="function token">MyComponent</span><span class="punctuation token">(</span><span class="punctuation token">)</span> <span class="punctuation token">{</span>
  <span class="comment token">// initialize the component here</span>
<span class="punctuation token">}</span></code></pre>

<h4 id="Class_declaration">Class declaration</h4>

<p>Declare the class prototype, using a form similar to this.</p>

<pre class="brush: js line-numbers  language-js"><code class="language-js">MyComponent<span class="punctuation token">.</span>prototype <span class="operator token">=</span> <span class="punctuation token">{</span>
  <span class="comment token">// properties required for XPCOM registration:</span>
  classDescription<span class="punctuation token">:</span> <span class="string token">"unique text description"</span><span class="punctuation token">,</span>
  classID<span class="punctuation token">:</span>          Components<span class="punctuation token">.</span><span class="function token">ID</span><span class="punctuation token">(</span><span class="string token">"{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}"</span><span class="punctuation token">)</span><span class="punctuation token">,</span>
  contractID<span class="punctuation token">:</span>       <span class="string token">"@example.com/xxx;1"</span><span class="punctuation token">,</span>

  <span class="comment token">// [optional] custom factory (an object implementing nsIFactory). If not</span>
  <span class="comment token">// provided, the default factory is used, which returns</span>
  <span class="comment token">// |(new MyComponent()).QueryInterface(iid)| in its createInstance().</span>
  _xpcom_factory<span class="punctuation token">:</span> <span class="punctuation token">{</span> <span class="punctuation token">.</span><span class="punctuation token">.</span><span class="punctuation token">.</span> <span class="punctuation token">}</span><span class="punctuation token">,</span>

  <span class="comment token">// [optional] an array of categories to register this component in.</span>
  _xpcom_categories<span class="punctuation token">:</span> <span class="punctuation token">[</span><span class="punctuation token">{</span>
    <span class="comment token">// Each object in the array specifies the parameters to pass to</span>
    <span class="comment token">// nsICategoryManager.addCategoryEntry(). 'true' is passed for</span>
    <span class="comment token">// both aPersist and aReplace params.</span>
    category<span class="punctuation token">:</span> <span class="string token">"some-category"</span><span class="punctuation token">,</span>
    <span class="comment token">// optional, defaults to the object's classDescription</span>
    entry<span class="punctuation token">:</span> <span class="string token">"entry name"</span><span class="punctuation token">,</span>
    <span class="comment token">// optional, defaults to the object's contractID (unless</span>
    <span class="comment token">// 'service' is specified)</span>
    value<span class="punctuation token">:</span> <span class="string token">"..."</span><span class="punctuation token">,</span>
    <span class="comment token">// optional, defaults to false. When set to true, and only if 'value'</span>
    <span class="comment token">// is not specified, the concatenation of the string "service," and the</span>
    <span class="comment token">// object's contractID is passed as aValue parameter of addCategoryEntry.</span>
    service<span class="punctuation token">:</span> <span class="keyword token">true</span><span class="punctuation token">,</span>
    <span class="comment token">// optional array of applications' IDs in the form:</span>
    <span class="comment token">// [ "{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}", ... ]</span>
    <span class="comment token">// If this is defined, the component is registered in this</span>
    <span class="comment token">// category only on the specified applications.</span>
    apps<span class="punctuation token">:</span> <span class="punctuation token">[</span> <span class="punctuation token">.</span><span class="punctuation token">.</span><span class="punctuation token">.</span> <span class="punctuation token">]</span>
  <span class="punctuation token">}</span><span class="punctuation token">]</span><span class="punctuation token">,</span>

  <span class="comment token">// QueryInterface implementation, e.g. using the generateQI helper</span>
  QueryInterface<span class="punctuation token">:</span> XPCOMUtils<span class="punctuation token">.</span><span class="function token">generateQI</span><span class="punctuation token">(</span>
    <span class="punctuation token">[</span>Components<span class="punctuation token">.</span>interfaces<span class="punctuation token">.</span>nsIObserver<span class="punctuation token">,</span>
     Components<span class="punctuation token">.</span>interfaces<span class="punctuation token">.</span>nsIMyInterface<span class="punctuation token">,</span>
     <span class="string token">"nsIFoo"</span><span class="punctuation token">,</span>
     <span class="string token">"nsIBar"</span> <span class="punctuation token">]</span><span class="punctuation token">)</span><span class="punctuation token">,</span>

  <span class="comment token">// [optional] classInfo implementation, e.g. using the generateCI helper.</span>
  <span class="comment token">// Will be automatically returned from QueryInterface if that was</span>
  <span class="comment token">// generated with the generateQI helper.</span>
  classInfo<span class="punctuation token">:</span> XPCOMUtils<span class="punctuation token">.</span><span class="function token">generateCI</span><span class="punctuation token">(</span>
    <span class="punctuation token">{</span>classID<span class="punctuation token">:</span> Components<span class="punctuation token">.</span><span class="function token">ID</span><span class="punctuation token">(</span><span class="string token">"{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}"</span><span class="punctuation token">)</span><span class="punctuation token">,</span>
     contractID<span class="punctuation token">:</span> <span class="string token">"@example.com/xxx;1"</span><span class="punctuation token">,</span>
     classDescription<span class="punctuation token">:</span> <span class="string token">"unique text description"</span><span class="punctuation token">,</span>
     interfaces<span class="punctuation token">:</span> <span class="punctuation token">[</span>Components<span class="punctuation token">.</span>interfaces<span class="punctuation token">.</span>nsIObserver<span class="punctuation token">,</span>
                  Components<span class="punctuation token">.</span>interfaces<span class="punctuation token">.</span>nsIMyInterface<span class="punctuation token">,</span>
                  <span class="string token">"nsIFoo"</span><span class="punctuation token">,</span>
                  <span class="string token">"nsIBar"</span><span class="punctuation token">]</span><span class="punctuation token">,</span>
     flags<span class="punctuation token">:</span> Ci<span class="punctuation token">.</span>nsIClassInfo<span class="punctuation token">.</span>SINGLETON<span class="punctuation token">}</span><span class="punctuation token">)</span><span class="punctuation token">,</span>

  <span class="comment token">// ...component implementation...</span>
<span class="punctuation token">}</span><span class="punctuation token">;</span></code></pre>

<div class="note">
<p><strong>Note:</strong> The ability to register the component in a category only on specific applications by adding the apps field to a category entry was added in Gecko 2.</p>
</div>

<p>Notice that the <code>QueryInterface()</code> method implemented by the component simply calls the <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#generateQI%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#generateQI()"><code>generateQI()</code></a> method provided by the XPCOMUtils code module.</p>

<h4 id="Create_an_array_of_component_constructors">Create an array of component constructors</h4>

<p>You need to create an array that lists the constructors for each component. This array can of course have just one entry:</p>

<pre class="line-numbers  language-html"><code class="language-html">var components = [MyComponent];</code></pre>

<p>Here, we're calling the array <code>components</code>.</p>

<h4 id="Create_the_NSGetFactory()_or_NSGetModule()_entry_point">Create the NSGetFactory() or NSGetModule() entry point</h4>

<p>Finally, you need to implement the <code>NSGetModule()</code> entry point so Gecko can start up your component:</p>

<pre class="line-numbers  language-html"><code class="language-html">// "components" is the array created in the previous section
if ("generateNSGetFactory" in XPCOMUtils)
  var NSGetFactory = XPCOMUtils.generateNSGetFactory(components);  // Gecko 2.0+
else
  var NSGetModule = XPCOMUtils.generateNSGetModule(components);    // Gecko 1.9.x</code></pre>

<h2 id="Method_overview">Method overview</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <td><code>function <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#defineLazyGetter%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#defineLazyGetter()">defineLazyGetter</a>(aObject, aName, aLambda);</code></td>
  </tr>
  <tr>
   <td><code>function <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#defineLazyModuleGetter%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#defineLazyModuleGetter()">defineLazyModuleGetter</a>(aObject, aName, aResource, [optional] aSymbol);</code></td>
  </tr>
  <tr>
   <td><code>function <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#defineLazyServiceGetter%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#defineLazyServiceGetter()">defineLazyServiceGetter</a>(aObject, aName, aContract, aInterfaceName);</code></td>
  </tr>
  <tr>
   <td><code>function <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#generateNSGetFactory%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#generateNSGetFactory()">generateNSGetFactory</a>(componentsArray);</code></td>
  </tr>
  <tr>
   <td><code>function <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#generateCI%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#generateCI()">generateCI</a>(classInfo); </code></td>
  </tr>
  <tr>
   <td><code>function <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#generateQI%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#generateQI()">generateQI</a>(interfaces);</code></td>
  </tr>
  <tr>
   <td><code>void <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#importRelative%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#importRelative()">importRelative</a>(that, path, scope);</code></td>
  </tr>
  <tr>
   <td><code>generator <a href="https://developer.mozilla.org/ja/docs/XPCOMUtils.jsm$edit#IterSimpleEnumerator%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#IterSimpleEnumerator()">IterSimpleEnumerator</a>(enumerator, interface);</code></td>
  </tr>
  <tr>
   <td><code>generator <a href="https://developer.mozilla.org/ja/docs/XPCOMUtils.jsm$edit#IterStringEnumerator%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#IterStringEnumerator()">IterStringEnumerator</a>(enumerator);</code></td>
  </tr>
 </tbody>
</table>

<h2 id="Attributes">Attributes</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <td class="header">Attribute</td>
   <td class="header">Type</td>
   <td class="header">Description</td>
  </tr>
  <tr>
   <td><code>categoryManager</code></td>
   <td>{{ interface("nsICategoryManager") }}</td>
   <td>Returns a reference to {{ interface("nsICategoryManager") }}.</td>
  </tr>
 </tbody>
</table>

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

<h3 id="defineLazyGetter()">defineLazyGetter()</h3>

<p><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get">Getter functions in JavaScript</a> give you a way to define a property of an object, but not calculate the property's value until it is accessed. A getter defers the cost of calculating the value until the value is needed, and if it is never needed, you never pay the cost.</p>

<p>A "lazy getter" provides an additional optimization: the value is calculated the first time the getter is called, and is then cached (or <a href="https://en.wikipedia.org/wiki/Memoization">memoized</a>), so subsequent accesses return the cached value without recalculating it.</p>

<p>This means that you shouldn't use a lazy getter for a property whose value you expect to change, because the getter will not recalculate the value.</p>

<p><code>defineLazyGetter</code> takes three arguments:</p>

<ul>
 <li>the object to define the property on</li>
 <li>the name of the property defined</li>
 <li>the getter function itself, which returns the value and which will be called just once, the first time code tries to access the property.</li>
</ul>

<p>Example for this is seen at bottom of this page <a href="https://developer.mozilla.org/ja/docs/XPCOMUtils.jsm$edit#defineLazyGetter">here</a>.</p>

<pre><code>function defineLazyGetter(
  aObject,
  aName,
  aLambda
);</code> </pre>

<h6 id="Parameters">Parameters</h6>

<dl>
 <dt><code>aObject</code></dt>
 <dd>The object into which to add the new lazy getter function.</dd>
 <dt><code>aName</code></dt>
 <dd>The name of the getter function to create.</dd>
 <dt><code>aLambda</code></dt>
 <dd>A function that returns the value the getter should return. This function is called exactly once.  <code>this</code> will reference <code>aObject</code> during execution of the function.</dd>
</dl>

<h3 id="defineLazyModuleGetter()">defineLazyModuleGetter()</h3>

<p>Defines a getter on a specified object for a module. The module will not be imported until first use.</p>

<pre><code>function defineLazyModuleGetter(
  aObject,
  aName,
  aResource,
  aSymbol
);</code> </pre>

<h6 id="Parameters_2">Parameters</h6>

<dl>
 <dt><code>aObject</code></dt>
 <dd>The object to define the lazy getter on.</dd>
 <dt><code>aName</code></dt>
 <dd>The name of the getter to define on <code>aObject</code> for the module.</dd>
 <dt><code>aResource</code></dt>
 <dd>The URL used to obtain the module.</dd>
 <dt><code>aSymbol</code></dt>
 <dd>The name of the symbol exported by the module. This parameter is optional and defaults to <code>aName</code>.</dd>
</dl>

<h3 id="defineLazyServiceGetter()">defineLazyServiceGetter()</h3>

<p>Defines a function on a specified object which acts as a getter for a service. The service isn't obtained until the first time it's used.</p>

<pre class="line-numbers  language-html"><code class="language-html">function defineLazyServiceGetter(
  aObject,
  aName,
  aContract,
  aInterfaceName
);</code></pre>

<h6 id="Parameters_3">Parameters</h6>

<dl>
 <dt><code>aObject</code></dt>
 <dd>The object into which to add the new lazy service getter function.</dd>
 <dt><code>aName</code></dt>
 <dd>The name of the getter function to create.</dd>
 <dt><code>aContract</code></dt>
 <dd>The contract to use to obtain the service.</dd>
 <dt><code>aInterfaceName</code></dt>
 <dd>The name of the interface to query the service to.</dd>
</dl>

<p> </p>

<h3 id="generateNSGetFactory()">generateNSGetFactory()</h3>

<p> </p>

<p>Generates the <code>NSGetFactory()</code> function along with the factory definition.</p>

<pre class="line-numbers  language-html"><code class="language-html">Function generateNSGetFactory(
  componentsArray
);</code></pre>

<h6 id="Parameters_4">Parameters</h6>

<dl>
 <dt><code>componentsArray</code></dt>
 <dd>An array of component constructors.</dd>
</dl>

<h6 id="Return_value">Return value</h6>

<p>A function that will return the factory for the components and can be assigned to <code>NSGetFactory</code> global variable.</p>

<h3 id="generateCI()">generateCI()</h3>

<p>Generates an {{ interface("nsIClassInfo") }} implementation for a component. The returned object should be assigned to the <code>classInfo</code> property of a JS object, the <code>QueryInterface()</code> function generated by <code>generateQI</code> will return it automatically then.</p>

<pre class="line-numbers  language-html"><code class="language-html">function generateCI(
  classInfo
);</code></pre>

<h6 id="Parameters_5">Parameters</h6>

<dl>
 <dt>classInfo</dt>
 <dd>An object containing the optional properties <code>interfaces</code>, <code>contractID</code>, <code>classDescription</code>, <code>classID</code>, <code>flags</code>. This parameter should not be the component itself because that would cause a memory leak.</dd>
</dl>

<h6 id="Return_value_2">Return value</h6>

<p>An {{ interface("nsIClassInfo") }} implementation returning the values of the properties from the <code>classInfo</code> parameter in its various properties.</p>

<h6 id="Exceptions_thrown">Exceptions thrown</h6>

<p>This method throws an exception with the message "In generateCI, don't use a component for generating classInfo" if <code>classInfo</code> parameter is an XPCOM component.</p>

<h3 id="generateQI()">generateQI()</h3>

<p>Generates a <code>QueryInterface()</code> function implementation. You need to assign the returned function to the <code>QueryInterface</code> property of a JavaScript object.</p>

<p>When the generated method is invoked on that object, it checks to see if the specified IID is listed in the array specified by the <code>interfaces</code> parameter; if it is, <code>this</code> (that is, the object itself) is returned. Otherwise, <code>null</code> is returned.</p>

<pre class="line-numbers  language-html"><code class="language-html">function generateQI(
  interfaces
);</code></pre>

<h6 id="Parameters_6">Parameters</h6>

<dl>
 <dt>interfaces</dt>
 <dd>An array of interfaces implemented by the component.</dd>
</dl>

<h6 id="Return_value_3">Return value</h6>

<p>A <code>QueryInterface()</code> function implementation.</p>

<h6 id="Remarks">Remarks</h6>

<p>When you implement an interface that inherits from another one, you should generally list all the base interfaces explicitly, except for {{ Interface("nsISupports") }}. For example, if your component implements {{ Interface("nsIStreamConverter") }}:</p>

<pre class="brush: js line-numbers  language-js"><code class="language-js">MyComponent<span class="punctuation token">.</span>prototype <span class="operator token">=</span> <span class="punctuation token">{</span>
  QueryInterface<span class="punctuation token">:</span> XPCOMUtils<span class="punctuation token">.</span><span class="function token">generateQI</span><span class="punctuation token">(</span><span class="punctuation token">[</span>
    Components<span class="punctuation token">.</span>interfaces<span class="punctuation token">.</span>nsIRequestObserver<span class="punctuation token">,</span>
    Components<span class="punctuation token">.</span>interfaces<span class="punctuation token">.</span>nsIStreamListener<span class="punctuation token">,</span>
    Components<span class="punctuation token">.</span>interfaces<span class="punctuation token">.</span>nsIStreamConverter<span class="punctuation token">,</span>
  <span class="punctuation token">]</span><span class="punctuation token">)</span><span class="punctuation token">,</span>

  <span class="comment token">// ...methods...</span>
<span class="punctuation token">}</span></code></pre>

<h3 id="importRelative()">importRelative()</h3>

<p>Imports a JavaScript code module given the calling JavaScript code module's global object (you should specify <code>this</code>) and a path relative to that module. This lets modules bundled in a package load one another without having to hard-code full paths.</p>

<pre class="line-numbers  language-html"><code class="language-html">void importRelative(
  that,
  path,
  scope
);</code></pre>

<h6 id="Parameters_7">Parameters</h6>

<dl>
 <dt><code>that</code></dt>
 <dd>The JavaScript Object of the calling JavaScript code module's global scope. You should simply pass <code>this</code>.</dd>
 <dt><code>path</code></dt>
 <dd>The relative path of the JavaScript code module to import.</dd>
 <dt><code>scope</code></dt>
 <dd>An optional object to import into; if omitted, the object passed in for the <code>that</code> parameter is used.</dd>
</dl>

<h6 id="Remarks_2">Remarks</h6>

<p>This lets an extension bundle its own JavaScript code modules within itself and have them load one another. For example, if an extension named "MyExtension" bundles <code>foo.jsm</code> and <code>bar.jsm</code>, and foo.jsm needs to load <code>bar.jsm</code>, it can do so like this:</p>

<pre class="deki-transform line-numbers  language-html"><code class="language-html">Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
XPCOMUtils.importRelative(this, "bar.jsm");</code></pre>

<p>In other words: <code>importRelative</code> will only work from other code modules (such as JSM files). It will NOT work from overlay scripts or <code>bootstrap.js</code> or etc. Details can be found here: {{bug("628669")}}</p>

<h3 id="IterSimpleEnumerator()">IterSimpleEnumerator()</h3>

<p>Wraps an {{ Interface("nsISimpleEnumerator") }} instance into a JavaScript generator that can be easily iterated over.</p>

<pre class="line-numbers  language-html"><code class="language-html">generator IterSimpleEnumerator(
  enumerator,
  interface
);</code></pre>

<h6 id="Parameters_8">Parameters</h6>

<dl>
 <dt><code>enumerator</code></dt>
 <dd>The {{ Interface("nsISimpleEnumerator") }} instance to iterate over.</dd>
 <dt><code>interface</code></dt>
 <dd>The expected interface for each element.</dd>
</dl>

<h6 id="Return_value_4">Return value</h6>

<p>A generator yielding enumerated objects.</p>

<h6 id="Example">Example</h6>

<pre class="brush: js line-numbers  language-js"><code class="language-js"><span class="keyword token">const</span> nsIFile <span class="operator token">=</span> Components<span class="punctuation token">.</span>interfaces<span class="punctuation token">.</span>nsIFile<span class="punctuation token">;</span>
<span class="keyword token">for</span> <span class="punctuation token">(</span><span class="keyword token">var</span> file <span class="keyword token">in</span> XPCOMUtils<span class="punctuation token">.</span><span class="function token">IterSimpleEnumerator</span><span class="punctuation token">(</span>dir<span class="punctuation token">.</span>directoryEntries<span class="punctuation token">,</span> nsIFile<span class="punctuation token">)</span><span class="punctuation token">)</span>
  console<span class="punctuation token">.</span><span class="function token">log</span><span class="punctuation token">(</span>file<span class="punctuation token">.</span>path<span class="punctuation token">)</span><span class="punctuation token">;</span></code></pre>

<h3 id="IterStringEnumerator()">IterStringEnumerator()</h3>

<p>Wraps an {{ Interface("nsIStringEnumerator") }} or {{ Interface("nsIUTF8StringEnumerator") }} instance into a JavaScript generator that can be easily iterated over.</p>

<pre class="line-numbers  language-html"><code class="language-html">generator IterStringEnumerator(
  enumerator
);</code></pre>

<h6 id="Parameters_9">Parameters</h6>

<dl>
 <dt><code>enumerator</code></dt>
 <dd>The {{ Interface("nsIStringEnumerator") }} or {{ Interface("nsIUTF8StringEnumerator") }} instance to iterate over.</dd>
</dl>

<h6 id="Return_value_5">Return value</h6>

<p>A generator yielding enumerated strings.</p>

<h6 id="Example_2">Example</h6>

<pre class="brush: js line-numbers  language-js"><code class="language-js"><span class="keyword token">for</span> <span class="punctuation token">(</span><span class="keyword token">var</span> section <span class="keyword token">in</span> XPCOMUtils<span class="punctuation token">.</span><span class="function token">IterStringEnumerator</span><span class="punctuation token">(</span>iniParser<span class="punctuation token">.</span><span class="function token">getSections</span><span class="punctuation token">(</span><span class="punctuation token">)</span><span class="punctuation token">)</span><span class="punctuation token">)</span>
  console<span class="punctuation token">.</span><span class="function token">log</span><span class="punctuation token">(</span>section<span class="punctuation token">)</span><span class="punctuation token">;</span></code></pre>

<h2 id="Post-registration_callback">Post-registration callback</h2>

<p>The post-registration callback called by <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#generateModule%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#generateModule()"><code>generateModule()</code></a> should have the following signature:</p>

<pre class="line-numbers  language-html"><code class="language-html">postRegister(
  nsIComponentManager compMgr,
  nsIFile fileSpec,
  componentsArray
);</code></pre>

<h6 id="Parameters_10">Parameters</h6>

<dl>
 <dt><code>compMgr</code></dt>
 <dd>An {{ interface("nsIComponentManager") }} instance to use for managing the component.</dd>
 <dt><code>fileSpec</code></dt>
 <dd>An {{ interface("nsIFile") }} instance for... what?</dd>
 <dt><code>componentsArray</code></dt>
 <dd>An array of the components, as passed to <code>generateModule()</code>.</dd>
</dl>

<p>The function doesn't need to return a value.</p>

<h2 id="Pre-unregistration_callback">Pre-unregistration callback</h2>

<p>The pre-unregistration callback passed to <a href="https://developer.mozilla.org/en/JavaScript_code_modules/XPCOMUtils.jsm#generateModule%28%29" title="en/JavaScript code modules/XPCOMUtils.jsm#generateModule()"><code>generateModule()</code></a> should have the following signature:</p>

<pre class="line-numbers  language-html"><code class="language-html">preUnregister(
  nsIComponentManager compMgr,
  nsIFile fileSpec,
  componentsArray
);</code></pre>

<h6 id="Parameters_11">Parameters</h6>

<dl>
 <dt><code>compMgr</code></dt>
 <dd>The {{ interface("nsIComponentManager") }} instance to use for managing the component.</dd>
 <dt><code>fileSpec</code></dt>
 <dd>An {{ interface("nsIFile") }} instance for... what?</dd>
 <dt><code>componentsArray</code></dt>
 <dd>The array of components passed to <code>generateModule()</code>.</dd>
</dl>

<p>This function doesn't need to return a value.</p>

<h2 id="Examples">Examples</h2>

<h3 id="defineLazyGetter">defineLazyGetter</h3>

<pre class="brush: js line-numbers  language-js"><code class="language-js"><span class="keyword token">var</span> myServices <span class="operator token">=</span> <span class="punctuation token">{</span><span class="punctuation token">}</span><span class="punctuation token">;</span>
Cu<span class="punctuation token">.</span><span class="keyword token">import</span><span class="punctuation token">(</span><span class="string token">'resource://gre/modules/XPCOMUtils.jsm'</span><span class="punctuation token">)</span><span class="punctuation token">;</span>

<span class="comment token">//set it up</span>
XPCOMUtils<span class="punctuation token">.</span><span class="function token">defineLazyGetter</span><span class="punctuation token">(</span>myServices<span class="punctuation token">,</span> <span class="string token">'as'</span><span class="punctuation token">,</span> <span class="keyword token">function</span> <span class="punctuation token">(</span><span class="punctuation token">)</span> <span class="punctuation token">{</span> <span class="keyword token">return</span> Cc<span class="punctuation token">[</span><span class="string token">'@mozilla.org/alerts-service;1'</span><span class="punctuation token">]</span><span class="punctuation token">.</span><span class="function token">getService</span><span class="punctuation token">(</span>Ci<span class="punctuation token">.</span>nsIAlertsService<span class="punctuation token">)</span> <span class="punctuation token">}</span><span class="punctuation token">)</span><span class="punctuation token">;</span>

<span class="comment token">//when you need to use it</span>
myServices<span class="punctuation token">.</span><span class="keyword token">as</span><span class="punctuation token">.</span><span class="function token">showAlertNotification</span><span class="punctuation token">(</span><span class="string token">'chrome://branding/content/icon64.png'</span><span class="punctuation token">,</span> <span class="string token">'this was lazyloaded'</span><span class="punctuation token">,</span> <span class="string token">'this is a notification from myServices.as'</span><span class="punctuation token">,</span> <span class="keyword token">null</span><span class="punctuation token">,</span> <span class="keyword token">null</span><span class="punctuation token">)</span><span class="punctuation token">;</span></code></pre>

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

<ul>
 <li><a class="internal" href="https://developer.mozilla.org/en/JavaScript_code_modules/Using" title="en/JavaScript code modules/Using JavaScript code
    modules">Using JavaScript code modules</a></li>
 <li><a class="internal" href="https://developer.mozilla.org/en/JavaScript_code_modules" title="en/JavaScript code
    modules">JavaScript code modules</a></li>
 <li><a href="http://dxr.mozilla.org/mozilla-central/source/js/xpconnect/loader/XPCOMUtils.jsm">XPCOMUtils.jsm source on DXR</a></li>
</ul>