渲染问题

Question

  paypal.Buttons({
    createOrder: function(data, actions) {
      // This function sets up the details of the transaction, including the amount and line item details.
      return actions.order.create({
        purchase_units: [{
          amount: {
            value: "<?php echo($_SESSION["total_price"]); ?>"
          }
        }]
      });
    },
    onApprove: function(data, actions) {
      // This function captures the funds from the transaction.
      return actions.order.capture().then(function(details) {
        // This function shows a transaction success message to your buyer.
        alert('Transaction completed by ' + details.payer.name.given_name);
      });
    }
  }).render('.Paypal');

该按钮在页面重新加载时呈现，但在首次访问该页面时显示 NOT 。

value: "<?php echo($_SESSION["total_price"]); ?>"

我觉得PHP代码在呈现之前就没有到达目的地，从而导致错误

有什么想法吗？
非常感谢帮助