case 'generate_buy_form':
$id = intval($post['id']);
$product = $db->super_query("SELECT * FROM `cabinet_products` WHERE `id` = '{$id}'");
$form = get_tpl( $cabinet_config['template'], '/shop/buy_form.tpl');
$form = str_replace("{product-image}", $product['block_image'], $form);
$form = str_replace("{product-name}", $product['block_name'], $form);
$form = str_replace("{product-price}", $product['block_price'], $form);
$form = str_replace("{product-id}", $product['id'], $form);
$row = [ 'response' => $form, ];
ajax_html('success', 'Предметы с сервера успешно получены', $row);
break;<script>
var price = "{product-price}";
var amount = document.getElementById('product_amount');
let totalamount = document.getElementById('totalamount');
let totalcost = document.getElementById('totalcost');
function fullprice() {
totalamount.textContent = 'Стоимось за ' + amount.value + ' шт:';
totalcost.textContent = price * amount.value + ' рублей';
}
amount.oninput = function () {
fullprice();
}
</script>
<form action id="buy_product_form">
<div class="modal-product">
<div class="modal-product__image">
<img src="{product-image}" alt="">
</div>
<div class="modal-product__content">
<div class="modal-product__info">
<span>Блок:</span>
<span>{product-name}</span>
</div>
<div class="modal-product__info">
<span>Стоимость за шт:</span>
<span>{product-price} рублей</span>
</div>
<div class="modal-product__info">
<span id="totalamount">Стоимость за шт:</span>
<span id="totalcost">{product-price} рублей</span>
</div>
<div class="modal-product__info">
<span class="mb-1">Количество:</span>
<div class="form-group mb-1">
<input type="number" class="form-control" name="product_amount" id="product_amount" placeholder="Количество" required>
</div>
</div>
</div>
</div>
<button type="button" class="cabinet-button" onclick="buy_product('{product-id}')">Купить</button>
</form>
var totalamount = document.getElementById('totalamount');
var totalcost = document.getElementById('totalcost');