The SDK provides several events you can listen to control the payment flow:

Event	Description	Handler Signature
`onReady`	Called when checkout is initialized and ready	`(event: CheckoutReadyEvent) => void`
`onSubmit`	Called when user submits payment. Call `event.resolve()` to continue	`(event: PaymentSubmitEvent) => void`
`onSuccess`	Called when payment succeeds. Call `event.resolve()` to complete	`(event: PaymentSuccessEvent) => void`
`onError`	Called when payment fails. Call `event.resolve()` to allow retry	`(event: PaymentErrorEvent) => void`
`onInfoUpdated`	Called when info (e.g., cart contents) is updated	`(event: InfoUpdatedEvent) => void`
`onShippingUpdated`	Called when shipping selection changes	`(event: ShippingUpdatedEvent) => void`

Using Events for Custom Logic

You can use the onSubmit event to run async logic before payment is processed:

onSubmit: async (event) => {
  // Perform async merchant logic
  // e.g., create internal order, freeze stock, validate inventory
  try {
    await merchantApi.createOrder({
      items: cartItems,
      customer: customerInfo
    });
    // Async done - continue with payment
    event.resolve();
  } catch (error) {
    // Cancel payment if order creation fails
    event.reject(error);
  }
}

You can use the onSuccess event to handle post-payment logic:

onSuccess: async (event) => {
  // Log the transaction
  console.log('Transaction ID:', event.transaction?.transactionId);
  console.log('Order ID:', event.orderId);

  // Redirect to return URL or show success page
  window.location.href = event.returnUrl;

  event.resolve();
}