title: Can a variable be made readonly in Node.js
body: <p>I want to prevent a variable from being changed. Specifically a property of an Object:</p>
  
  <pre><code>var foo = { bar: 'baz' };
  
  // do something to foo to make it readonly
  
  foo.bar = 'boing'; // should throw exception
  </code></pre>
  
  <p>Can this be done?</p>