Can I overwrite a constructor in javascript?
<p>I just learned that I <a href="http://stackoverflow.com/questions/13383345/how-do-i-access-this-javascript-property">can overwrite a method</a> in a Javascript class, as shown below, but what about the actual constructor?</p>

<p>If possible, how do I do it without instantiating the class?</p>

<pre><code>var UserModel = (function() {
  var User;
  User = function() {}; // &lt;- I want to overwrite this whilst keeping below methods
  User.prototype.isValid = function() {};
  return User;
})();
</code></pre>
