title: What is a good way to test for inheritance of Backbone-extended constructors?
body: <p>How can I test if a constructor extends another constructor, Backbone.js-style, where inheritance is set up via Backbone's <code>extend</code> method? And don't say <code>instanceof</code> :). I'm not talking about objects. I'm talking about constructors.</p>
  
  <p>E.g.: Take a constructor like the one produced by the following code:</p>
  
  <pre><code>var MyRouter = Backbone.Router.extend();
  </code></pre>
  
  <p>Now, in another spot in the code, how can you test that somewhere in its prototype chain, <code>var my_router = new MyRouter</code> has the properties of <code>Backbone.Router.prototype</code>?</p>