I’ve asked the chatgpt, and wacthed all the youtube videos, I think the code is fine but why the ajax didnt send any responses.

in my script js file:

$('#loginForm').submit(function (e) {
  e.preventDefault();

  // var formData = new FormData(document.getElementById("loginForm"));

  $.ajax({
    type: "POST",
    url: "loginHandle.php",
    data: $('#loginForm').serialize(),
    // processData: false,
    // contentType: false,
    dataType: "json",
    success: function (response) {
      console.log("Response received:", response); 
      if (response.status == 422) {
        $("#errorMessage").text(response.errors);
        // document.getElementById("errorMessage").textContent = response.errors;
        console.log(response.errors);
      } else if (response.status == 200) {
        window.location.href = "index.php";
      }
    },
  });
});

in my loginHandle php:

<?php
require_once("sql_connection.php");
$database = new SQLConnect();
$query = $database->connect();
$error = array();
$status = 400;
if ($_SERVER["REQUEST_METHOD"] == "POST" && isset($_POST['login-request'])) {
  $email = $_POST['email'];

  $checkEmail = $query->prepare("SELECT * FROM `người dùng` WHERE `Email` = :email");
  $checkEmail->bindParam(':email', $email);
  $checkEmail->execute();
  if ($checkEmail->rowCount() == 0) {
    $error['email'] = "Email không tồn tại !";
    $status = 422;
  } else {
    $user = $checkEmail->fetch();
    if (!password_verify($_POST['password'], $user['Mật khẩu'])) {
      $error['password'] = "Mật khẩu không đúng !";
      $status = 422;
    }
  }
  if (!$error) {
    session_start();
    $_SESSION['user_id'] = $user['Mã người dùng'];
    // if ($user['Phân loại'] == "Quản trị viên")
    //   header("location:admin/admin.php");
    // else
    //   header("location:index.php");
    $status = 200;
    $error = '';
  }
  // header('Content-Type: application/json');
  $response = ['status' => $status, 'errors' => $error];
  echo json_encode($response);
}

The ajax had loaded the php file, and it sent 200 ok, but the response is empty.