成功不会出现

Help to make a conclusion successful transmission of data. I tried in different ways, but it does not work. By clicking on the "Send" button the data is sent, but the message "Data sent successfully". I need it to form disappeared and instead of it there was a message "Data sent successfully"

    submitHandler: function(form){
        var $form = $(form);
        $.post('form.php', $form.serialize(), function(data){
            if (!data || data.status !== 'ok') {
                $form.find('input').addClass('error');
                return false;
            }
            forms.fadeOut('slow', function(){
                $('.form--success').fadeIn('fast');
            });
        }, 'json');
        return false;
    }
});

form.php

if(isset($_POST['submit'])) {
    $to = "example@example.com";
    $subject = "Contact Form";
    $phone = $_POST['phone'];
    $mail = $_POST['mail'];
    $headers = "From: $phone<$mail>
";
    $body = "From: $phone<$mail>
 Phone Number: $phone
 E-Mail:      $mail
";
    mail($to, $subject, $body, $headers);
    exit();
 } 

http://37.230.210.96/ - testing site

You're not targeting the right element to fade out. You have:

var form = $(form);

To fade that out you would use this:

form.fadeOut('slow', function(){
    $('.form--success').fadeIn('fast');
});

forms != form