ajax - Check the username before registering in Wordpress -

i created script checking username before registering, not work. returns mistake. script in functions.php:

function check_user_login_init(){      /* Подключаем скрипт для проверки */     wp_register_script('ajax-login-script', get_template_directory_uri() . '/js/ajax-login-script.js', array('jquery') );      wp_enqueue_script('ajax-login-script');      /* Локализуем параметры скрипта */     wp_localize_script( 'ajax-login-script', 'ajax_check_login_object', array(        'ajaxurl' => admin_url( 'admin-ajax.php' ),       'loadingmessage' => __('verified data, wait second...')     ));      // Разрешаем запускать функцию check_user_login() пользователям без привелегий     add_action( 'wp_ajax_nopriv_check_user_login', 'check_user_login' );       }      if (!is_user_logged_in()) {         add_action('init', 'check_user_login_init');     }      function check_user_login(){          // Первым делом проверяем параметр безопасности         check_ajax_referer( 'ajax-login-nonce', 'security' );          // Получаем данные из поля #user_login формы и проверяем их         $username = $_request['username'];          $sanitized_user_name = sanitize_user( $username, 1 );         if ( username_exists( $sanitized_user_name )) {                  echo json_encode(array('avaliblename'=>false, 'message'=>__('choose name!')));             } else {                  echo json_encode(array('avaliblename'=>false, 'message'=>__('ok!')));             }          die();         exit;     } 

and here js:

jquery(document).ready(function($) {     $('.register_box #registration #user_login').on('keyup', function(e){              $.ajax({                 beforesend: function(){                     $('.register_box .status_registration').show().text(ajax_login_object.loadingmessage);                 },                 type: 'post',                 datatype: 'json',                 url: ajax_check_login_object.ajaxurl,                 cache: false,                 data: {                      'action': 'check_user_login', //calls wp_ajax_nopriv_checkuserlogin                     'username': $('.register_box #user_login').val()                        },                 datafilter: function(){                     $('.register_box .status_registration').html('data processed...');                 },                 error:  function(){                      $('.register_box .status_registration').html('something wrong...');                      },                 success: function(data){                           $('.register_box .status_registration').html(data.message);                 }         });         e.preventdefault();     }); }); 

when try inputting user name in google chrome returns error:

uncaught typeerror: cannot read property 'message' of null

could this?

this javascript error due data.message not being set. check in network tab of developer toolbar check what's coming server.

side-note: wouldn't hurt enable debugging on server-side idea logs of what's going on. here's how in wp-config.php:

define('wp_debug', true); define('wp_debug_display', false); // turn forced display off define('wp_debug_log',     true);  // turn logging wp-content/debug.log on 

and executing following line anywhere push wp-content/debug.log (which can monitor):

error_log('started processing array:'); error_log(print_r($array, true)); 

finally, rid of die(); , keep exit; statement.