JSFiddle - React, Tailwind, and code Playground

HTML

<form method="post" class="ms2_form">
    <input type="hidden" name="ms2_default_action" value="cart/qweqwe" />
    <input type="text" name="count" value="1">
    <button class="btn" type="submit" name="ms2_action" value="cart/add">Кнопка!</button>
</form>

JavaScript

(function (window, document, $, undefined) {$(document).ready(function($){
var submit			= ':submit[name=ms2_action]';
    form			= '.ms2_form';
    $doc			= $(document);

    $doc.on('submit', form, function (e) {
        alert('submit!');
        
        e.preventDefault();
    }).on('click', submit, function (e) {
        alert('click!');
    });
});})(this, document, jQuery);