PHP看不到serializeArray()从ajax发布的数据

$.ajax({
    url: 'your_php_script.php',
    type: 'POST',
    contentType: 'application/json', // 设置内容类型为 JSON
    data: JSON.stringify($('form').serializeArray()), // 将序列化的数组转换为 JSON 字符串
    success: function(response) {
        console.log(response);
    },
    error: function(xhr, status, error) {
        console.error(error);
    }
});

<?php
// 获取原始 POST 数据
$jsonData = file_get_contents('php://input');
// 解码 JSON 数据
$data = json_decode($jsonData, true);

// 现在你可以访问数据了
foreach ($data as $item) {
    echo "Name: " . htmlspecialchars($item['name']) . ", Value: " . htmlspecialchars($item['value']) . "<br>";
}
?>

<form id="myForm">
    <input type="text" name="username" value="JohnDoe">
    <input type="password" name="password" value="secret">
    <button type="button" id="submitBtn">Submit</button>
</form>

$(document).ready(function() {
    $('#submitBtn').click(function() {
        $.ajax({
            url: 'process_form.php',
            type: 'POST',
            contentType: 'application/json',
            data: JSON.stringify($('#myForm').serializeArray()),
            success: function(response) {
                alert('Data sent successfully!');
            },
            error: function(xhr, status, error) {
                alert('An error occurred: ' + error);
            }
        });
    });
});

<?php
$jsonData = file_get_contents('php://input');
$data = json_decode($jsonData, true);

if (json_last_error() === JSON_ERROR_NONE) {
    foreach ($data as $item) {
        echo "Name: " . htmlspecialchars($item['name']) . ", Value: " . htmlspecialchars($item['value']) . "<br>";
    }
} else {
    echo "Invalid JSON data.";
}
?>