title: Server not seeing the JSON sent in javascript ajax request
body: <p>I'm trying to make an ajax request in straight javascript (jQuery is not available to me) with some JSON parameters.
  The javascript:</p>
  
  <pre><code>var params = {'ajax': true, 'albumid': albumid, 'sequencenum': sequencenum};
  var xhr = new XMLHttpRequest();
  xhr.onreadystatechange=function()
  {
      if (xhr.readyState==4 &amp;&amp; xhr.status==200)
      {
          console.log(xhr.responseText);
      }
  }
  xhr.open("GET","viewpicture.php",true);
  xhr.setRequestHeader("Content-Type", "application/json")
  console.log("sending request");
  xhr.send(JSON.stringify(params));
  </code></pre>
  
  <p>In viewpicture.php, a var_dump($_GET) yields an empty array. What am I doing wrong?</p>