如何使用ajax调用php include语句

I have an index.php file. My wish is that, when clicking on a button (which is in index.php) an AJAX request should load about.php and include it inside a div tag in index.php.

Below is my code. But this is not working:

index.php:

<a href=javascript:onClick('about.php')>About</a>
<div id='dynamo'>
   <?php 
       if($_POST){
       $page=$_POST['page'];                   
       include $page;
       }
   ?>
</div>

PageSelect.js

 function onClick(text){       
 $.ajax({
     type:"POST",
     url:"index.php",
     datastring:'page='+text          
  });     
 }

You need something like this (with Jquery):

HTML:

<a href="#" id="click">About</a>
<div id="render"></div>

JS:

$(document).ready(function () {

    $('#click').click(function () {
        $.ajax({
            url: "about.php",
            success: function (response) {
                $('#render').html(response);
            }
        });
    });

});

JSFiddle