Symfony 5 ajax post form - ajax

Question

I need to make dynamic form in symfony 5 with ajax.
I make post request with axios on input value change on main route "/".
This route call my controller and i call dump() function for debug my request but i don't have any params on my request.
I looked in my network and my data is posted well. But I don't receive params on my request controller :/
On my view
<script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.21.0/axios.min.js"></script>
<script>
cat = document.getElementById("article_category")
token = document.querySelector("#article__token");
title = document.querySelector("#article_title");
cat.addEventListener("change", function (e) {
let form = document.querySelector("form")
let data = {}
data[title.getAttribute("name")] = title.value
data[token.getAttribute("name")] = token.value
data[cat.getAttribute("name")] = cat.value
axios.post("https://127.0.0.1:8000/", data).then(res => {
str = res.data
var parser = new DOMParser();
var doc = parser.parseFromString(str, 'text/html')
console.log(doc);
}).catch(function (error) {
console.log(error);
});
})
</script>
My Controller
/**
* #Route("/", name="article")
*/
public function index(Request $request, EntityManagerInterface $em): Response
{
$article = new Article();
$form = $this->createForm(ArticleType::class, $article);
$form->handleRequest($request);
if ($request->getMethod() == 'POST') {
dump($request);
}
if ($form->isSubmitted() && $form->isValid()) {
$em->persist($article);
$em->flush();
}
return $this->render('article/index.html.twig', [
"form" => $form->createView(),
]);
}
FormType
$builder
->add('title')
->add('category')
->add('Submit', SubmitType::class);
$builder->get('category')->addEventListener(
FormEvents::POST_SUBMIT,
function (FormEvent $event) {
$form = $event->getForm();
if ($form->getData()->getName() == "Cat 0") {
$form->getParent()->add('tag', EntityType::class, [
'class' => Tag::class,
]);
}
}
);