title: JavaScript. How to hook aceessing to object
body: <p>Where a lot of information about hooking functions. But. Is it possible to hook accessing to objects?
  For example.
  We have "navigator" object. It has a lot of params. We need to hook accessing to UserAgent param. Is it possible? Mybe I may use define of setter/getter? Or something else...</p>
  
  <p>As we know where no way to replace navigator object (it is read only). So we cant slove it simple like:</p>
  
  <pre><code>var blabla = navigator;
  blabla.UserAgent = "myagent";
  </code></pre>
  
  <p>etc</p>
  
  <p>Regards!</p>
  
  <p>ps
  sorry for my english :)</p>