WordPress Ajax Getting Response “Null”

I am trying to get ID of post on HOME page .So far my coding is

wp_enqueue_script( 'my-ajax-request', get_stylesheet_directory_uri() . '/js/ajax.js', array( 'jquery' ) );
wp_localize_script( 'my-ajax-request', 'MyAjax', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) ) );
add_action('wp_ajax_nopriv_ajax_request', 'ajax_handle_request');
add_action('wp_ajax_ajax_request', 'ajax_handle_request');


function ajax_handle_request(){
$postID = $_POST['id'];
if (isset($_POST['id'])){
    $post_id = $_POST['id'];
}else{
    $post_id = "";
}

global $post;
$post = get_post($postID);

$response = array( 
    'sucess' => true, 
    'post' => $post,
    'id' => $postID , 
);

// generate the response
print json_encode($response);

// IMPORTANT: don't forget to "exit"
exit;
}

And My jquery

jQuery(document).ready(function($) {
$('h1.entry-title a').click(function(event) {
    event.preventDefault();
var id = $(this).data('id');

$.ajax({
  type: 'POST',
  url: MyAjax.ajaxurl,
  data: {'action' : 'ajax_request', 'id': id},
  dataType: 'json',
  success: function(data) {
    alert(data['post']);
  }
});     

return false;
});
});

But I am getting alert Null instead of getting the id of post.

You are rendering the json data the wrong way.

Change the success to the below:–

success: function(data) {
    alert(data.id);
    // Now you can similarly render the other details like details.success
}