Drupal: Update item by ajax.

foo.js

(function($) {
  Drupal.behaviors.Foo = {
    attach:function (context, settings) {
      // unbind() because click events firing multiple times.
      $('#foo a.update', context).unbind().click(function (event) {
        // Get parrent of item.
        var item = $(this).closest(".item");
        
        // Get some data of item.
        var uid = item.data('uid');
        
        // Get some data of another items.
        var existed = [];
        $('#foo .item', context).each(function() {
          existed.push($(this).data('uid'));
        });

        item.hide(300);

        $.ajax({
          type: 'POST',
          url: window.location.protocol + "//" + window.location.host + '/foo/ajax',
          cache: false,
          dataType: 'html',
          data: {
            uid: uid,
            existed: existed
          },
          complete: function(msg) {
            item.html(msg.response).show(300);
            
            Drupal.attachBehaviors(context);
          }
        });

        return false;
      });
    }
  }
})(jQuery);

foo.module

<?php
/**
 * Implements hook_menu().
 */
function foo_menu() {
  $items = array();

  $items['foo/ajax'] = array(
    'page callback' => '_foo_ajax',
    'page arguments' => array(),
    'access callback' => 'user_is_logged_in',
    'type' => MENU_CALLBACK,
  );

  return $items;
}

function _foo_ajax() {
  $uid = $_POST['uid'];
  $existed = $_POST['existed'];
  
  // Do something here
  
  // Store data for ajax.
  $vars['attributes_array']['data-uid'] = $account->uid;

  // Return to ajax.
  print $html;
  exit;
}