PaymentRequest

@inject Bit.Butil.PaymentHandler paymentHandler

@code {
    // What a page controls: the account shown next to this app in the payment sheet, and which
    // fields the handler collects itself rather than letting the browser ask for them.
    private async Task Configure()
    {
        await paymentHandler.SetUserHint("[email protected]");

        var hint = await paymentHandler.GetUserHint();

        var enabled = await paymentHandler.EnableDelegations(
            new[] { "shippingAddress", "payerEmail" });
    }
}

// The handling itself. Neither event can be answered from a page: the browser wakes the worker with
// no tab necessarily open, which is why an installed handler needs an active registration.
self.addEventListener('canmakepayment', event => {
    // Answered before the sheet is drawn, to decide whether this app is offered at all.
    event.respondWith(true);
});

self.addEventListener('paymentrequest', event => {
    // Opening a window is how a handler shows its own UI; the response is whatever that window
    // resolves with, and its shape is the payment method's business rather than the browser's.
    event.respondWith(new Promise(resolve => {
        event.openWindow('/wallet/confirm').then(client => {
            self.addEventListener('message', message => resolve(message.data));
        });
    }));
});

{
  "//": "Served at the payment method's own URL, which is the payment method identifier itself.",
  "default_applications": ["https://wallet.example/manifest.json"],
  "supported_origins": ["https://wallet.example"]
}