how to pass JSON data to php using ajax post
<p>Here is the code: (the #debug div text is shown below)</p>

<pre><code>$("#debug").text(JSON.stringify(data));
// Try to save to a file
$.ajax({
    type: 'POST',
    url: './json.php',
    dataType: 'json',
    data: JSON.stringify(data),            
    success: function(xhr, status, errorMessage) {
        if( xhr.responseText == "Success" ) {
            alert("Success!");
        } else {
            alert("response was "+xhr.responseText);
        }
    },
    error: function(xhr, status, errorMessage) {
        $("#debug").append("RESPONSE: "+xhr.responseText+", error: "+errorMessage);
    }
});
</code></pre>

<p>The JSON.php page is:</p>

<pre><code>&lt;?php
openlog("scriptLog.txt", LOG_PID | LOG_PERROR, LOG_LOCAL0);
   $json = $_POST['json'];
// open syslog, include the process ID and also send
// the log to standard error, and use a user defined
// logging mechanism
    syslog(LOG_DEBUG, "Received Data");

   if (json_decode($json) != null) { /* sanity check */
    $file = fopen('./data.json','w+');
     fwrite($file, json_decode($json));
     fclose($file);
   } else {
     syslog(LOG_DEBUG,"Failure");
     return "Failure, json decode is null";
   }
   closelog();
   return "Success";
?&gt;
</code></pre>

<p>In the log I get:</p>

<p>Mar 14 14:50:54  scriptLog.txt[21902] : Received Data</p>

<p>Mar 14 14:50:54  scriptLog.txt[21902] : Failure</p>

<p>In the debug div text I get:</p>

<pre><code>{"1457981454959":{"id":1457981454959,"code":"1","title":"Test","date":"22/03/2016","description":"a Task"}}RESPONSE: , error: SyntaxError: JSON Parse error: Unexpected EOF
</code></pre>

<p>1)  How can I examine the posted data? I.e. "Received Data: "+WHAT in syslog to see its structure.
2)  JSON parse error?  Most examples I see use this stringify function.  then they use json_decode to get the values.  Why the parse error?</p>