title: jQuery JSONP Call towards PHP backend: No HTTP response
body: <p><strong>Update IV / Current status:</strong> I've now confirmed trough another question that the character encoding of the file is fine and not the cause of the problem. I've also tested against another server and the error still persists. It does however work towards localhost.
  <em>So to summarize:</em> JSONP call works towards localhost, but when running against external domains the response from the server is empty (no header / no http response code). When copying the requested URL and inserting it directly in a browser, the output is correct with correct formating (utf-8 / json). </p>
  
  <p><strong>Fiddle:</strong> <a href="http://jsfiddle.net/5SJvp/1/" rel="nofollow">http://jsfiddle.net/5SJvp/1/</a></p>
  
  <p><strong>Update III:</strong> I'm now able to get it working succesfully on localhost. However, using the exact same code (both client and server) towards my production domain it still fails. The response from the server is "empty" meaning to say it returns no http status code. </p>
  
  <p><strong>Update II:</strong> After some more debugging I noticed that the response does not include an http status code. This probably is the cause of my problem? I assume this means there is something wrong server side, but I cannot for the life of me see where. </p>
  
  <p><strong>Update I:</strong> Snip from jQuery where to request seems to halt.</p>
  
  <pre><code>// Do send the request
  // This may raise an exception which is actually
  // handled in jQuery.ajax (so no try/catch here)
  xhr.send( ( s.hasContent &amp;&amp; s.data ) || null ); 
  </code></pre>
  
  <p>Params (from Firebug)</p>
  
  <pre><code>_   1356655864905
  callback    jQuery18308375673194150332_1356655863817
  p   0522
  pl  12
  s   false
  secret  ##############################
  u   request12341299
  </code></pre>
  
  <p>Request (from Firebug)</p>
  
  <pre><code>Accept  text/javascript, application/javascript, application/ecmascript, application/x-ecmascript, */*; q=0.01
  Accept-Encoding gzip, deflate
  Accept-Language nb-no,nb;q=0.9,no-no;q=0.8,no;q=0.6,nn-no;q=0.5,nn;q=0.4,en-us;q=0.3,en;q=0.1
  Connection  keep-alive
  Host    localhost:8888
  Referer http://localhost:8888/popup.html
  User-Agent  Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/20100101 Firefox/17.0
  X-Requested-With    XMLHttpRequest
  </code></pre>
  
  <p><strong>Original question:</strong></p>
  
  <p>I'm struggling with what seems to be a common problem, but I've yet to find a solution. I'm trying to execute a very simple jsonp call using jQuery. The problem is that either a) nothing is happening or b), the response from the server is empty. </p>
  
  <p>I've tried several different approaches, using both the $.ajax method and the $.getJSON method. Both produce the same faulty result. Using the code below nothing happens: Using the Chrome debugger I can see that it simply stops its execution halffway trough the method. However using Wireshark I can see that the client performs the three way handshake and thusly prepars to send data, it just fails to do that.</p>
  
  <p>If I remove the <strong>callback=?</strong> it does execute, however the response is malformed (or at least, I think so since I can only see a response marked with a red line in Firebug).</p>
  
  <pre><code>$.ajax({
       url: "http://mydomain.com/asd.php", //"http://localhost:8888/index.php",
       dataType: 'jsonp',
       type: 'GET',
       data: {p:p, u:u, s:symbols, pl:pl, secret:secret},
       contentType: "application/json; charset=utf-8",
       async: false,
       success: function(data){
          console.log("What " + data.test); 
       }, 
       error: function(data){
           console.log("failed for some reason");
       }
   }); 
  </code></pre>
  
  <p>Server code ($callback = $_GET["callback"]</p>
  
  <pre><code>&lt;?php header('content-type: application/json; charset=utf-8');
  .
  .
  .
  $data = array
  (
      "message" =&gt; $message,
      "status" =&gt; $statuscode,
      "length" =&gt; strlen($message)        
  );
  
  echo $callback . '('.json_encode($data) .')';
  exit;       
  ?&gt;
  </code></pre>
  
  <p>Here is the server response with manually typed input.</p>
  
  <pre><code>funcName({"message":"!0b7(cb6Gv40","status":"OK","length":12})
  </code></pre>