Is this a jQuery bug? $.post vs $.ajax
<p>UPDATE: my code may be confusing and contain errors. But here is what I'm trying to do with both $.ajax and $.post
----I want to send JSON to php and receive plain text. But $_POST is empty&lt;-why?-----</p>

<p>I found the $_POST to be empty if I use $.ajax, but contains the right content when using $.post
Update: Requirement--
I need to use a JSON request. But problem is $_POST is empty in php, see Var_dump
This is my script</p>

<pre><code>    &lt;script&gt;
    $(document).ready(function(){
        $("#submit").click(function(){
            $.ajax({
                type: "POST",
                url: "Ajax_example.php",
                data: {"field": $("#field").val()},
                contentType: "application/json; charset=utf-8", 
                success: function(msg){
                    alert("NEW DATA:"+msg);
                }
            });
    /*      $.post("Ajax_example.php", {"field": $("#field").val()}, 
                    function(msg){
                        alert("NEW DATA:"+msg);
                    });*/
            return false;
        })

    });
    &lt;/script&gt;
</code></pre>

<p>This is my php</p>

<pre><code>    &lt;?php

    echo var_dump($_POST);


    ?&gt;
</code></pre>

<p>With the above, $.post portion are comments. With the $.ajax portion running, it alerts out only "NEW DATA:"
But If I do it the other way around, I will get whatever I put in #field</p>
