Why isn't JSON data coming from the controller in AJAX?

Question

AJAX

Hello dear IT experts.
I turn to you again for help.
There is HTML code and Jquery user registration

<div id="registerBox">
    <div class="menuCaption showHidden" onclick="showRegisterBox()">Регистрация</div>
    <div id="registerBoxHidden">
        <p>email</p>
        <input type="text" id="email" name="email" value=""><br/>
        <p>Пароль</p>
        <input type="password" id="pwd1" name="pwd1" value=""><br/>
        <p>Повторить Пароль</p>
        <input type="password" id="pwd2" name="pwd2" value=""><br/><br/>
        <input type="button" onclick="registerNewUser()" value="Зарегистрироватся">
    </div>
    </div>

function registerNewUser(){
    let postData = getData('#registerBox');
    console.log(postData);
    $.ajax({
        type:'POST',
        async:true,
        data:postData,
        url:"/user/register/",
        dataType:'json',
        success:function(data){
            if(data['success']){
                alert('Регистрация прошла успешно!');
                // блок в левом столбце
                $('#registerBox').hide();

                // $('#userLink').attr('href','/user/');
                // $('#userLink').html(data['userName']);
                // $('#userBox').show();

                // страница заказа
                // $('#loginBox').hide();
                // $('#btnSaveOrder').show();
            }
            else{
                alert(data['message']);
            }
        } 
});
}

There is a user registration controller

<!-- контроллер пользователей -->

<?php

//подключаем модули
include_once '../models/CategoriesModel.php';
include_once '../models/UsersModel.php';

function registerAction(){
    $email = isset($_REQUEST['email'])? $_REQUEST['email']:null;
    $email = trim($email);
    $pwd1 = isset($_REQUEST['pwd1']) ? $_REQUEST['pwd1']:null;
    $pwd2 = isset($_REQUEST['pwd2']) ? $_REQUEST['pwd2']:null;

    $phone = isset($_REQUEST['phone'])? $_REQUEST['phone']:null;
    $address = isset($_REQUEST['address'])? $_REQUEST['address']:null;
    $name = isset($_REQUEST['name'])? $_REQUEST['name']:null;
    $name = trim($name);

    $resData = null;
    $resData = checkRegisterParams($email,$pwd1,$pwd2);
    
    if(!$resData && checkUserEmail($email)){
        $resData['success'] = false;
        $resData['message'] = "Пользователь с таким email('{$email}') уже зарегистрирован.";
        
    }

    if(!$resData){
        $pwdMD5 = md5($pwd1);
        $userData = registerNewUser($email,$pwdMD5,$name,$phone,$address);
        if($userData['success']){
            $resData['message'] = "Пользователь успешно зарегистрирован.";
            $resData['success'] = 1;
            $userData = $userData[0];
            $resData['userName'] = $userData['name'] ? $userData['name']:$userData['email'];
            $resData['userEmail'] = $email;

            $_SESSION['user'] = $userData;
            $_SESSION['user']['displayName'] = $userData['name'] ? $userData['name']:$userData['email'];
        }
        else{
            $resData['success'] = 0;
            $resData['message'] = "Ошибка регистрации";
        }
    }
    echo json_encode($resData);
}
?>

and model

<!-- модель для таблицы пользователей -->

<?php
// регистрация нового пользователя

function registerNewUser($email,$pwdMD5,$name,$phone,$address){
    global $db;
    $email = htmlspecialchars(mysqli_real_escape_string($db,$email));
    $name = htmlspecialchars(mysqli_real_escape_string($db,$name));
    $phone = htmlspecialchars(mysqli_real_escape_string($db,$phone));
    $address = htmlspecialchars(mysqli_real_escape_string($db,$address));
    

    $sql = "INSERT INTO `users`(`email`,`pwd`,`name`,`phone`,`address`) VALUES('{$email}','{$pwdMD5}','{$name}','{$phone}','{$address}')";
    $rs = mysqli_query($db,$sql);
    
    if($rs){
        $sql = "SELECT * FROM `users` WHERE `email` = '{$email}' AND `pwd` = '{$pwdMD5}' LIMIT 1";
        $rs = mysqli_query($db,$sql);
        $rs = createSmartyRsArray($rs);
        if($rs[0]){
            $rs['success'] = 1;
        }
        else{
            $rs['success'] = 0;
        }
    }
    else{
        $rs['success'] = 0;
    }
    return $rs;
}



//проверка параметров для регистрации пользователей

function checkRegisterParams($email,$pwd1,$pwd2){
    $res = null;

    if(!$email){
        $res['success'] = false;
        $res['message'] = 'Введите имайл';
    }

    if(!$pwd1){
        $res['success'] = false;
        $res['message'] = 'Введите пароль';
    }

    if(!$pwd2){
        $res['success'] = false;
        $res['message'] = 'Введите повтор пароля';
    }

    if($pwd1 != $pwd2){
        $res['success'] = false;
        $res['message'] = 'Пароли не совпадают';
    }

   
    return $res;
}
// проверка почты(есть ли имайл в БД)

function checkUserEmail($email){
    global $db;
    $email = mysqli_real_escape_string($db,$email);
    $sql = "SELECT id FROM `users` WHERE `email` = '{$email}'";
    $rs = mysqli_query($db,$sql);
    $res = createSmartyRsArray($rs);
    return $res;
}
?>

registerAction returns $resData. If you check through var_dump, it will be like this:

array(4) {
  ["message"]=>
  string(71) "Пользователь успешно зарегистрирован."
  ["success"]=>
  int(1)
  ["userName"]=>
  string(10) "[email protected]"
  ["userEmail"]=>
  string(10) "[email protected]"
}

Or, if there is already such an email, then it writes an error corresponding to the error in the code...
The user is added to the database. However, neither an alert with successful registration, nor the registration field is hidden.
There are no php errors. No errors are visible in network, except for the array.

Answer 1

You see the answer in the console. Is this valid JSON?
Remove var_dump and comments