Why does not the feedback form?

Welcome. There is a site on html, no admin, no nothing. But I preadvies feedback form and I got this link. Everything seems clear and logical, but for some reason I does not work and displays this error
js that appears in the error (mail.js):
(function ($) {
$(".contact-form").submit(function (event) {

 // Save in variable form id of the current form that fired the submit event
 let form = $('#' + $(this).attr('id'))[0];

 // Save variables in diva, which will display the error text
 let inpNameError = $(this).find('.contact-form__error_name');
 let inpEmailError = $(this).find('.contact-form__error_email');
 let inpTelError = $(this).find('.contact-form__error_tel');

 // Store in variable div, which will display a message of the form
 let formDescription = $(this).find('.contact-form__description');

 let fd = new FormData(form);
 url: "/mail/php/mail.php",
 type: "POST",
 data: fd,
 processData: false,
 contentType: false,
 success: function success(res) {
 let respond = $.parseJSON(res);

 if (respond.name) {
 } else {

 if (respond.tel) {
 } else {

 if (respond.email) {
 } else {

 if (respond.attantion) {
 formDescription.text(respond.attantion).css('color', '#e84a66').fadeIn();
 } else {

 if (respond.success) {
 setTimeout(() => {
 }, 4000);
 setTimeout(() => {
 }, 5000);

How to solve this problem?

Form code
<form class="contact-form" id="contact-form_1" method="POST" enctype="multipart/form-data">
 <p class="contact-form__description"></p>
 <div class="contact-form__input-wrapper">
 <input name="name" type="text" class="form-control contact-form__input contact-form__input_name" placeholder="Enter your name">
 <div class="contact-form__error contact-form__error_name"></div>

 <div class="contact-form__input-wrapper">
 <input name="tel" type="tel" class="form-control contact-form__input contact-form__input_tel"
 placeholder="Enter your phone">
 <div class="contact-form__error contact-form__error_tel"></div>

 <div class="contact-form__input-wrapper"> 
 <input name="email" type="email" class="form-control contact-form__input contact-form__input_email"
 placeholder="Enter your email">
 <div class="contact-form__error contact-form__error_email"></div>

 <button class="btn contact-form__button btn-green" type="submit"> Get price </button>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
 <script src="/mail/js/mail.js"></script>

April 7th 20 at 10:50
1 answer
April 7th 20 at 10:52
Error says that your client script sends data to the server, receives the response and assumes that the response in JSON format. But the server returns invalid JSON or something else.

Just open DevTools browser log network calls and see what gets you the server.
The network tab in chrome?
Then I did not understand. Like no failure - heber.Orn12 commented on April 7th 20 at 10:55
@heber.Orn12, Well, on screen I guess I can't - ressie50 commented on April 7th 20 at 10:58
@ressie50as primay the last line that appears when you press the "send" button, it says that jquery called mail.php. And that's it. Nothing interesnogo. Can be the case in js? Namely mail.js that comes in the archive with the above website - heber.Orn12 commented on April 7th 20 at 11:01
view that returns you the server
. It will be useful - ressie50 commented on April 7th 20 at 11:04

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