? In es6 or coffeescript, you can simply do:</p>
<pre><code class="language-javascript">class SuperCircle extends Circle
</code></pre>

<p>In plain old javascript, there's a convenient function in Pt to help with that:</p>
<pre><code class="language-javascript">Util.extend( SuperCircle, Circle)
</code></pre>

<p><a href="http://williamngan.github.io/pt/demo/index.html?name=space.add">This simple demo</a> shows a simple example of an extended class. See <a href="https://github.com/williamngan/pt/blob/master/