title: How to add getter to an existing object
body: <p>I can have a getter in a JavaScript object like this:</p>
  <pre><code>var member = {
      firstName:&quot;XYZ&quot;, 
      lastName:&quot;zzz&quot;, 
      get fullName(){ return (this.firstName + ' ' + this.lastName); }
  }
  </code></pre>
  <p>I can even add more properties on the fly, like this:</p>
  <pre><code>member.isGuest = true;
  </code></pre>
  <p>But, is there any way we can add getters to an existing object? Something like this:</p>
  <pre><code>member.isGuest = get isGuest(){ return this.firstName=='Guest'; }
  </code></pre>