title: Trying to understand server response that returns a javascript method
body: <p>I've seen this code today and I cannot understand why someone had to write something like this. It seems that this returns a javascript method. But why? How is that useful? Why not return the {id:123} immediately? The expiration date is the same as the Date but why? To prevent caching? </p>
  
  <pre><code>    &lt;?php
         header('Content­Type: text/plain');
         header('Expires: Tue, 30 Aug 2015 16:03:37 GMT');
         header('Date: Tue, 30 Aug 2015 16:03:37 GMT');
         header('Connection: close');
         echo "do({id:123})";
      ?&gt;
  </code></pre>