js

openWindow(url)

js

…
self.addEventListener('paymentrequest', async e => {
…
  // Retain a promise for future resolution
  // Polyfill for PromiseResolver at link below.
  resolver = new PromiseResolver();

  // Pass a promise that resolves when payment is done.
  e.respondWith(resolver.promise);
  // Open the checkout page.
  try {
    // Open the window and preserve the client
    client = await e.openWindow(checkoutURL);
    if (!client) {
      // Reject if the window fails to open
      throw 'Failed to open window';
    }
  } catch (err) {
    // Reject the promise on failure
    resolver.reject(err);
  };
});
…