The PaymentRequest method complete() of the Payment Request API notifies the user agent that the user interaction is over, and causes any remaining user interface to be closed.

This method must be called after the user accepts the payment request and the Promise returned by the PaymentRequest.show() method is resolved.

result Optional

A string indicating the state of the payment operation upon completion. It must be one of the following:

success

The payment was successfully processed. The user agent may or may not present some form of "payment successful" indication to the user.

fail

The payment was not successfully processed. The failure may or may not be announced to the user by the user agent, depending on its design.

unknown

The success or failure status of the transaction is unknown or irrelevant, and the user agent should not present any notification, even if it normally would. This is the default value.

Note: In older versions of the specification, an empty string, "", was used instead of unknown to indicate a completion without a known result state. See the Browser compatibility section below for details.

A Promise which resolves with no input value once the payment interface has been fully closed. If an error occurs, the promise instead rejects, returning one of the exceptions listed below.

AbortError DOMException

Returned if the document in which the payment request is taking place became inactive while the user interface was shown.

InvalidStateError DOMException

Returned if the payment has already completed, or complete() was called while a request to retry the payment is pending. You can't treat a payment as complete after requesting that the payment be tried again.

The following example sends payment information to a secure server using the Fetch API. It calls complete() with an answer appropriate to the status in the response.

// Initialization of PaymentRequest arguments are excerpted for the
//   sake of brevity.
const payment = new PaymentRequest(supportedInstruments, details, options);

payment
  .show()
  .then((paymentResponse) => {
    const fetchOptions = {
      method: "POST",
      credentials: include,
      body: JSON.stringify(paymentResponse),
    };
    const serverPaymentRequest = new Request("secure/payment/endpoint");
    fetch(serverPaymentRequest, fetchOptions)
      .then((response) => {
        if (response.status < 400) {
          paymentResponse.complete("success");
        } else {
          paymentResponse.complete("fail");
        }
      })
      .catch((reason) => {
        paymentResponse.complete("fail");
      });
  })
  .catch((err) => {
    console.error("Uh oh, something bad happened", err.message);
  });