Recommend a Payment App when User Has No Apps
In this example, if you select to pay with BobPay on this merchant page, it tries to
call PaymentRequest.show(), while intercepting the
NOT_SUPPORTED_ERR exception. If this payment method is not supported,
it redirects to the download page for BobPay.
For the purposes of the demo, imagine you have chosen an item and now you need to check out.
Payment Request success. Demo complete. No payment has been taken.
The Payment Request API is unsupported or was cancelled or failed. Here we can proceed with a fallback (not implemented for this demo).