title: Why can't I delete a mongoose model's object properties?
body: <p>When a user registers with my API they are returned a user object.  Before returning the object I remove the hashed password and salt properties.  I have to use</p>
  
  <pre><code>user.salt = undefined;
  user.pass = undefined;
  </code></pre>
  
  <p>Because when I try</p>
  
  <pre><code>delete user.salt;
  delete user.pass;
  </code></pre>
  
  <p>the object properties still exist and are returned.</p>
  
  <p>Why is that?</p>