custom element directives such as <code>&lt;md-checkbox&gt;</code> or <code>&lt;custom-input&gt;</code>
as required, using ngAria with <a href="api/ng/directive/ngRequired">ngRequired</a> will also add
<code>aria-required</code>. This tells accessibility APIs when a custom control is required.</p>
<h3 id="example">Example</h3>
<pre><code class="lang-html">&lt;md-checkbox ng-required=&quot;val&quot;&gt;&lt;/md-checkbox&gt;
</code></pre>
<p>Becomes:</p>
<pre><code class="lang-html">&lt;md-checkbox ng-required