What's the purpose of the following JS structure?
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/1643321/javascript-why-the-anonymous-function-wrapper">JavaScript: Why the anonymous function wrapper?</a>  </p>
</blockquote>



<p>Sometimes I see a structure like this in JS programs:</p>

<pre><code>(function() {
 // blah blah
})();
</code></pre>

<p>Any ideas what's this doing and what are its side-effects and benefits?</p>
