Aplicações Web mono página

/**
* Called on 'checkout' click
*/
function onCheckout(){
    // Create the order, based on your cart
    var order = {
        "amount":   990,
        "currency": "EUR",
        "orderId":  "myOrderId-999999",
        "customer": {
            "email": "sample@example.com"
        }
    };

    // Call merchant server to get form token and then display payment form
    getFormToken(order, displayPaymentForm, alert);
}

/**

* Get form token from merchant server
* @param order
* @param resolve
* @param reject
*/
function getFormToken(order, resolve, reject){
    var request = new XMLHttpRequest();

    // Open a new connection, using the POST request on the URL endpoint
    request.open('POST', 'YOUR_SERVER/payment/init', true);
    request.setRequestHeader('Content-Type', 'application/json');

    request.onload = function (){
        if (request.status >= 200 && request.status < 400) {
            resolve(this.response);
        }
        else
        {
            reject("Invalid server response. Code " + request.status);
        }
    };

    request.onerror = function (error){
        reject(error);
    };

    // Send request
    request.send(JSON.stringify(order));
}

/* Init payment form */
router.post('/init', function(req, res, next){
  var order = req.body;

  // TO DO: check that order is valid

  // Call CreatePayment web service to create the form token
  request.post({
    url: "https://api.lyra.com/api-payment/V4/Charge/CreatePayment",
    headers: {
      'Authorization': 'Basic Njk4NzYzNTc6dGVzdHBhc3N3b3JkX0RFTU9QUklWQVRFS0VZMjNHNDQ3NXpYWlEyVUE1eDdN',
      'Content-Type': 'application/json'
    },
    json: order
  }, function(error, response, body){
    if (body.status === 'SUCCESS')
    {
      // Send back the form token to the client side
      res.send(body.answer.formToken);
    }
    else
    {
      // Do your own error handling
      console.error(body);
      res.status(500).send('error');
    }
  });
});

/**
* Display the payment form with the argument form token
* @param formToken
*/
function displayPaymentForm(formToken){
    // Show the payment form
    document.getElementById('paymentForm').style.display = 'block';

    // Set form token
    KR.setFormToken(formToken);

    // Add listener for submit event
    KR.onSubmit(onPaid);
}

/**
 * Called when payment is finished
 * @param event
 */
function onPaid(event){
  if (event.clientAnswer.orderStatus === "PAID") {
    // Remove the payment form
    KR.removeForms();

    // Show success message
    document.getElementById("paymentSuccessful").style.display = "block";
  } else {
    // Show error message to the user
    alert("Payment failed !");
  }
}