title: How do I create an abstract base class in JavaScript?
body: <p>Is it possible to simulate abstract base class in JavaScript? What is the most elegant way to do it?</p>
  
  <p>Say, I want to do something like: -</p>
  
  <pre><code>var cat = new Animal('cat');
  var dog = new Animal('dog');
  
  cat.say();
  dog.say();
  </code></pre>
  
  <p>It should output: 'bark', 'meow'</p>