Самая лучшая форма отправки с AJAX

Файл index.php:

$(".jq_form").on('submit', function (event) {
    event.preventDefault();
    var t = $(this);
    var action = t.attr('action');
    var data = t.serialize();
    var submit = t.find('.form-submit');
    $.ajax({
        type: "POST",
        url: action,
        data: data,
        success: function (response) {
            try {
                var responseObj = JSON.parse(response);
                if (responseObj['status'] === true) {
                    submit.empty();
                    submit.append(responseObj['msg']);
                    submit.prop('disabled', true);
                } else {
                    console.log(response);
                }
            } catch (e) {
                console.log(response);
            }
        }
    });
});
//varaint vanila js:
document.addEventListener("DOMContentLoaded", function() {
    let forms = document.getElementsByClassName('form_class_for_JS');

    for (let form of forms) {
        form.onsubmit = function (event) {
            event.preventDefault();
            let url = this.getAttribute('action');
            let submit = this.querySelectorAll('.form_submit');
            let formData = new FormData(this);
            submit[0].innerHTML = '';
            submit[0].append('Загрузка...');
            submit[0].setAttribute('disabled', 'true');
            return fetch(url, {
                method: 'POST',
                body: formData  //data
            })
                .then(response => response.json())
                .then(data => {
                    if (data['status'] === true) {
                        submit[0].innerHTML = '';
                        submit[0].append(data.msg);
                        submit[0].setAttribute('disabled', 'true');
                        window.top.location = "/thankyou_page/";
                    } else {
                        console.log(data);// Prints result from `response.json()` in getRequest
                    }
                })
                .catch(error => console.error(error))
        };
    }
});

Файл ajax.php:

$to = 'mymail@mail.ru';
$subject = 'blabla';
$message = '';
$message .= 'name - '.preg_replace('/[^А-Яа-яA-Za-z]/','',$_POST['name']).PHP_EOL;
$message .= 'phone - '. (int)$_POST['phone'];
if (mail($to,$subject,$message)){
    echo json_encode(['status' =--> true,'msg' => 'Ваша заявка принята'],JSON_UNESCAPED_UNICODE); } 
else { 
    echo json_encode(['status' => false]); 
}