在PHP / AJAX中计算动态表单的总价格

I am making an ecommerce-like website.

I am trying to make a price calculator so customers can count total price for their product specification.

The specification variable is taken from a database, so the form is kind of dynamic.

I need to calculate the base price + (specification + specification + specification ) * quantity. you could also suggest me to choose from PHP / AJAX

Here is the form

<form method="GET" action="../action/calculate.php">
            <?php
                include "../connect.php";
                $slug = $_GET['slug'];
                $sql="SELECT * FROM product,options WHERE options.product_id = product.id AND product.slug = '$slug'"; 
                $result = $conn->query($sql);
                while ($data = $result->fetch_assoc()){
                $id = $data['id'];
                echo "
                <div class='form-group'>
                <label>".$data['options_title']."</label>
                <select name='".$data['options_title']."' class='form-control operator'>
                "
                ?>
                <?php
                $options_id = $data['options_id'];
                $sql2="SELECT * FROM options_value WHERE options_id = '$options_id' "; 
                $result2 = $conn->query($sql2);
                while ($data2 = $result2->fetch_assoc()){
                        echo "<option value='".$data2['price_add']."'>".$data2['options_value_title']." +IDR  ".number_format($data2['price_add'], 0, ',', '.')."</option>";
                }
                ?>
                <?php echo "
                </select>
                </div>
                ";
                }                   
                ?>
                <div class='form-group'>
                    <label>Jumlah</label>
                    <input type="number" name="jumlah" min="1" value="1" class="form-control">
                </div>
                <button type="submit" class="btn btn-success px-5 font-weight-bold">Lanjut</button>
        </form>

$bahan = $_GET['bahan'];
$laminating=$_GET['laminating'];
$jumlah=$_GET['jumlah'];

echo ($bahan + $laminating) * $jumlah;