PHP网络商店购物车实时小计

Question

我有一个像CART系统这样的网络商店，您可以将项目添加到购物车中，它们将出现在此处。我存储了产品的数量和价格。我也有一个+和 - 按钮，因此您可以将存储数量更改为1。只有一个函数丢失：当用户单击时，例如++<+<< /code>按钮，它将数量增加并立即将其存储在日期库中。但是可悲的是，它不会显示新的价格（将原始价格乘以新的数量值）。如果我重新加载页面，则价格将被乘以，但是在我单击+按钮后，我无法弄清楚如何立即显示新价格。我需要一些想法，您将如何做？

index.php

php：

$sql = "SELECT * FROM `table` WHEN 1";
$res = $con-> query($sql);
if ($res -> num_rows > 0) { $subtot = 0; // Subtotal variable to save the new subtotal
   while ($item = $res-> fetch_assoc()) {
      echo ''; // Display the items with their data using HTML
      // I also have the JS script here, so I can use the `+` and `-` button functions
      // I use ajax, and pass the product's id and the new quantity to a new .php file (for example up.php)
     // Add the values to the subtot varialbe
     $subtot += $item['price'] * $item['quantity']; // So on page refresh I get the item's price and value so I can multiply the price and show the subtotal.
     // I think somewhere here should be the code to update the `$subtotal` on the `+` button click to multiply the price with the new quantity, but I can't change php variables on js button clicks.
   }
}
echo $subtotal; // Display the subtotal

+按钮脚本：

document.getElementById("plusbutton").addEventListener("click", () => { if var bsi__data = new FormData(); bsi__data.append("pid", "'.$product['pid'].'"); bsi__data.append("quantity", document.getElementById("bspq__inp'.$product['pid'].'").value); bsi__data.append("price", "'.$product['product_price'].'");
$.ajax({
enctype: "multipart/form-data", type: "POST", url: "/assets/php/basket/q__up.php", data: bsi__data, dataType: "json", contentType: false, processData: false,
success: function(data) { console.log(data); su__refresh(); },
error: function (data) { console.log("error"); console.log(data); }
});
});

最后是up.php

if ($stmt = $con->prepare('UPDATE cart SET quantity = ? WHERE pid = ? AND uid = ?')) {
            $stmt->bind_param('iii', $_POST['quantity'], $_POST['pid'], $uid);$stmt->execute(); die('ok');
        } else { die ("error");