Payment Request API

• Allow the user agent to act as intermediary between a merchant, user, and payment method provider.
• Enable user agents to streamline the user's payment experience by taking into account user preferences, merchant information, security considerations, and other factors.
• Standardize (to the extent that it makes sense) the communication flow between a merchant, user agent, and payment method provider.
• Enable a payment method provider to bring more secure payment transactions to the web.

The following are out of scope for this specification:

• Create a new payment method.
• Integrate directly with payment processors.

When constructing a new PaymentRequest, a merchant uses the first argument (methodData) to list the different ways a user can pay for things (e.g., credit cards, Apple Pay, Google Pay, etc.). More specifically, the methodData sequence contains PaymentMethodData dictionaries containing the payment method identifiers for the payment methods that the merchant accepts and any associated payment method specific data (e.g., which credit card networks are supported).

const methodData = [
  {
    supportedMethods: "https://example.com/payitforward",
    data: {
      payItForwardField: "ABC",
    },
  },
  {
    supportedMethods: "https://example.com/bobpay",
    data: {
      merchantIdentifier: "XXXX",
      bobPaySpecificField: true,
    },
  },
];

When constructing a new PaymentRequest, a merchant uses the second argument of the constructor (details) to provide the details of the transaction that the user is being asked to complete. This includes the total of the order and, optionally, some line items that can provide a detailed breakdown of what is being paid for.

const details = {
  id: "super-store-order-123-12312",
  displayItems: [
    {
      label: "Sub-total",
      amount: { currency: "GBP", value: "55.00" },
    },
    {
      label: "Value-Added Tax (VAT)",
      amount: { currency: "GBP", value: "5.00" },
    },
  ],
  total: {
    label: "Total due",
    // The total is GBP£65.00 here because we need to
    // add shipping (below). The selected shipping
    // costs GBP£5.00.
    amount: { currency: "GBP", value: "65.00" },
  },
};

Here we see an example of how to add two shipping options to the details.

const shippingOptions = [
  {
    id: "standard",
    // Shipping by truck, 2 days
    label: "🚛  Envío por camión (2 dias)",
    amount: { currency: "EUR", value: "5.00" },
    selected: true,
  },
  {
    id: "drone",
    // Drone shipping, 2 hours
    label: "🚀 Drone Express (2 horas)",
    amount: { currency: "EUR", value: "25.00" }
  },
];
Object.assign(details, { shippingOptions });

Here we see how to add a processing fee for using a card on a particular network. Notice that it requires recalculating the total.

// Certain cards incur a $3.00 processing fee.
const cardFee = {
  label: "Card processing fee",
  amount: { currency: "AUD", value: "3.00" },
};

// Modifiers apply when the user chooses to pay with
// a card.
const modifiers = [
  {
    additionalDisplayItems: [cardFee],
    supportedMethods: "https://example.com/cardpay",
    total: {
      label: "Total due",
      amount: { currency: "AUD", value: "68.00" },
    },
    data: {
      supportedNetworks: networks,
    },
  },
];
Object.assign(details, { modifiers });

Some financial transactions require a user to provide specific information in order for a merchant to fulfill a purchase (e.g., the user's shipping address, in case a physical good needs to be shipped). To request this information, a merchant can pass a third optional argument (options) to the PaymentRequest constructor indicating what information they require. When the payment request is shown, the user agent will request this information from the end user and return it to the merchant when the user accepts the payment request.

const options = {
  requestPayerEmail: false,
  requestPayerName: true,
  requestPayerPhone: false,
  requestShipping: true,
}

Having gathered all the prerequisite bits of information, we can now construct a PaymentRequest and request that the browser present it to the user:

async function doPaymentRequest() {
  try {
    const request = new PaymentRequest(methodData, details, options);
    // See below for a detailed example of handling these events
    request.onshippingaddresschange = ev => ev.updateWith(details);
    request.onshippingoptionchange = ev => ev.updateWith(details);
    const response = await request.show();
    await validateResponse(response);
  } catch (err) {
    // AbortError, SecurityError
    console.error(err);
  }
}
async function validateResponse(response) {
  try {
    const errors = await checkAllValuesAreGood(response);
    if (errors.length) {
      await response.retry(errors);
      return validateResponse(response);
    }
    await response.complete("success");
  } catch (err) {
    // Something went wrong...
    await response.complete("fail");
  }
}
// Must be called as a result of a click
// or some explicit user action.
doPaymentRequest();

Prior to the user accepting to make payment, the site is given an opportunity to update the payment request in response to user input. This can include, for example, providing additional shipping options (or modifying their cost), removing items that cannot ship to a particular address, etc.

const request = new PaymentRequest(methodData, details, options);
// Async update to details
request.onshippingaddresschange = ev => {
  ev.updateWith(checkShipping(request));
};
// Sync update to the total
request.onshippingoptionchange = ev => {
  // selected shipping option
  const { shippingOption } = request;
  const newTotal = {
    currency: "USD",
    label: "Total due",
    value: calculateNewTotal(shippingOption),
  };
  ev.updateWith({ total: newTotal });
};
async function checkShipping(request) {
  try {
    const { shippingAddress } = request;

    await ensureCanShipTo(shippingAddress);
    const { shippingOptions, total } = await calculateShipping(shippingAddress);

    return { shippingOptions, total };
  } catch (err) {
    // Shows error to user in the payment sheet.
    return { error: `Sorry! we can't ship to your address.` };
  }
}

A developer can use the shippingAddressErrors member of the PaymentDetailsUpdate dictionary to indicate that there are validation errors with specific attributes of a ContactAddress. The shippingAddressErrors member is a AddressErrors dictionary, whose members specifically demarcate the fields of a physical address that are erroneous while also providing helpful error messages to be displayed to the end user.

request.onshippingaddresschange = ev => {
  ev.updateWith(validateAddress(request.shippingAddress));
};
function validateAddress(shippingAddress) {
  const error = "Can't ship to this address.";
  const shippingAddressErrors = {
    city: "FarmVille is not a real place.",
    postalCode: "Unknown postal code for your country.",
  };
  // Empty shippingOptions implies that we can't ship
  // to this address.
  const shippingOptions = [];
  return { error, shippingAddressErrors, shippingOptions };
}

It's expected that data in a PaymentResponse will be POSTed back to a server for processing. To make this as easy as possible, PaymentResponse can use the default toJSON steps (i.e., .toJSON()) to serializes the object directly into JSON. This makes it trivial to POST the resulting JSON back to a server using the Fetch Standard:

async function doPaymentRequest() {
  const payRequest = new PaymentRequest(methodData, details);
  const payResponse = await payRequest.show();
  let result = "";
  try {
    const httpResponse = await fetch("/process-payment", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: payResponse.toJSON(),
    });
    result = httpResponse.ok ? "success" : "fail";
  } catch (err) {
    console.error(err);
    result = "fail";
  }
  await payResponse.complete(result);
}
doPaymentRequest();

To indicate that a cross-origin iframe is allowed to invoke the payment request API, the allow attribute along with the "payment" keyword can be specified on the iframe element.

<iframe
  src="https://cross-origin.example"
  allow="payment">
</iframe>

If the iframe will be navigated across multiple origins that support the Payment Request API, then one can set allow to "payment *". The Permissions Policy specification provides further details and examples.

The PaymentRequest is constructed using the supplied sequence of PaymentMethodData methodData including any payment method specific data, the PaymentDetailsInit details, and the PaymentOptions options.

The PaymentRequest(methodData, details, options) constructor MUST act as follows:

1. If this's relevant global object's associated Document is not allowed to use the "payment" permission, then throw a "SecurityError" DOMException.
2. Establish the request's id:
   1. If details.id is missing, add an id member to details and set its value to a UUID [RFC4122].
3. Let serializedMethodData be an empty list.
4. Process payment methods:
   1. If the length of the methodData sequence is zero, then throw a TypeError, optionally informing the developer that at least one payment method is required.
   2. Let seenPMIs be the empty set.
   3. For each paymentMethod of methodData:
      1. Run the steps to validate a payment method identifier with paymentMethod.supportedMethods. If it returns false, then throw a RangeError exception. Optionally, inform the developer that the payment method identifier is invalid.
      2. Let pmi be the result of parsing paymentMethod.supportedMethods with basic URL parser:
         1. If failure, set pmi to paymentMethod.supportedMethods.
      3. If seenPMIs contains pmi throw a RangeError DOMException optionally informing the developer that this payment method identifier is a duplicate.
      4. Append pmi to seenPMIs.
      5. If the data member of paymentMethod is missing, let serializedData be null. Otherwise, let serializedData be the result of serialize paymentMethod.data into a JSON string. Rethrow any exceptions.
      6. If serializedData is not null, and if the specification that defines the paymentMethod.supportedMethods specifies an additional data type:
         1. Let object be the result of JSON-parsing serializedData.

         2. Let idl be the result of converting object to an IDL value of the additional data type. Rethrow any exceptions.

         3. Run the steps to validate payment method data, if any, from the specification that defines the paymentMethod.supportedMethods on object. Rethrow any exceptions.

            Note

            These step assures that any IDL type conversion and validation errors are caught as early as possible.

      7. Add the tuple (paymentMethod.supportedMethods, serializedData) to serializedMethodData.
5. Process the total:
   1. Check and canonicalize total amount details.total.amount. Rethrow any exceptions.
6. If the displayItems member of details is present, then for each item in details.displayItems:
   1. Check and canonicalize amount item.amount. Rethrow any exceptions.
7. Let selectedShippingOption be null.
8. If the requestShipping member of options is present and set to true, process shipping options:
   1. Let options be an empty sequence<PaymentShippingOption>.
   2. If the shippingOptions member of details is present, then:
      1. Let seenIDs be an empty set.
      2. For each option in details.shippingOptions:
         1. Check and canonicalize amount item.amount. Rethrow any exceptions.
         2. If seenIDs contains option.id, then throw a TypeError. Optionally, inform the developer that shipping option IDs must be unique.
         3. Otherwise, append option.id to seenIDs.
         4. If option.selected is true, then set selectedShippingOption to option.id.
   3. Set details.shippingOptions to options.
9. Let serializedModifierData be an empty list.
10. Process payment details modifiers:
    1. Let modifiers be an empty sequence<PaymentDetailsModifier>.
    2. If the modifiers member of details is present, then:
       1. Set modifiers to details.modifiers.
       2. For each modifier of modifiers:
          1. If the total member of modifier is present, then:
             1. Check and canonicalize total amount modifier.total.amount. Rethrow any exceptions.
          2. If the additionalDisplayItems member of modifier is present, then for each item of modifier.additionalDisplayItems:
             1. Check and canonicalize amount item.amount. Rethrow any exceptions.
          3. If the data member of modifier is missing, let serializedData be null. Otherwise, let serializedData be the result of serialize modifier.data into a JSON string. Rethrow any exceptions.
          4. Add the tuple (modifier.supportedMethods, serializedData) to serializedModifierData.
          5. Remove the data member of modifier, if it is present.
    3. Set details.modifiers to modifiers.
11. Let request be a new PaymentRequest.
12. Set request.[[handler]] to null.
13. Set request.[[options]] to options.
14. Set request.[[state]] to "created".
15. Set request.[[updating]] to false.
16. Set request.[[details]] to details.
17. Set request.[[serializedModifierData]] to serializedModifierData.
18. Set request.[[serializedMethodData]] to serializedMethodData.
19. Set request.[[response]] to null.
20. Set the value of request's shippingOption attribute to selectedShippingOption.
21. Set the value of the shippingAddress attribute on request to null.
22. If options.requestShipping is set to true, then set the value of the shippingType attribute on request to options.shippingType. Otherwise, set it to null.
23. Return request.

When getting, the id attribute returns this PaymentRequest's [[details]].id.

The show(optional detailsPromise) method MUST act as follows:

1. Let request be this.
2. If the relevant global object of request does not have transient activation, the user agent MAY:
   1. Return a promise rejected with with a "SecurityError" DOMException.

   Note

   This allows the user agent to not require user activation, for example to support redirect flows where a user activation may not be present upon redirect. See 19.9 User activation requirement for security considerations.

   See also issue #1022 for discussion around providing more guidance in the specification on when user agents should or should not require a user activation for show().

3. Otherwise, consume user activation of the relevant global object.
4. Let document be request's relevant global object's associated Document.
5. If document is not fully active, then return a promise rejected with an "AbortError" DOMException.
6. If document's visibility state is not "visible", then return a promise rejected with an "AbortError" DOMException.

7. Optionally, if the user agent wishes to disallow the call to show() to protect the user, then return a promise rejected with a "SecurityError" DOMException. For example, the user agent may limit the rate at which a page can call show(), as described in section 19. Privacy and Security Considerations.

8. If request.[[state]] is not "created" then return a promise rejected with an "InvalidStateError" DOMException.
9. If the user agent's payment request is showing boolean is true, then:
   1. Set request.[[state]] to "closed".
   2. Return a promise rejected with an "AbortError" DOMException.
10. Set request.[[state]] to "interactive".
11. Let acceptPromise be a new promise.
12. Set request.[[acceptPromise]] to acceptPromise.

13. Optionally:

    1. Reject acceptPromise with an "AbortError" DOMException.
    2. Set request.[[state]] to "closed".
    3. Return acceptPromise.

    Note

    This allows the user agent to act as if the user had immediately aborted the payment request, at its discretion. For example, in "private browsing" modes or similar, user agents might take advantage of this step.

14. Set request's payment-relevant browsing context's payment request is showing boolean to true.
15. Return acceptPromise and perform the remaining steps in parallel.
16. Let handlers be an empty list.
17. For each paymentMethod tuple in request.[[serializedMethodData]]:
    1. Let identifier be the first element in the paymentMethod tuple.
    2. Let data be the result of JSON-parsing the second element in the paymentMethod tuple.
    3. If the specification that defines the identifier specifies an additional data type, then convert data to an IDL value of that type. Otherwise, convert data to object.
    4. If conversion results in an exception error:
       1. Set request.[[state]] to "closed".
       2. Reject acceptPromise with error.
       3. Set request's payment-relevant browsing context's payment request is showing boolean to false.
       4. Terminate this algorithm.
    5. Let registeredHandlers be a list of registered payment handlers for the payment method identifier.

       Note: Payment Handler registration

    6. For each handler in registeredHandlers:
       1. Let canMakePayment be the result of running handler's steps to check if a payment can be made with data.
       2. If canMakePayment is true, then append handler to handlers.
18. If handlers is empty, then:
    1. Set request.[[state]] to "closed".
    2. Reject acceptPromise with "NotSupportedError" DOMException.
    3. Set request's payment-relevant browsing context's payment request is showing boolean to false.
    4. Terminate this algorithm.

19. Present a user interface that will allow the user to interact with the handlers. The user agent SHOULD prioritize the user's preference when presenting payment methods. The user interface SHOULD be presented using the language and locale-based formatting that matches the document's document element's language, if any, or an appropriate fallback if that is not available.

    Note: Localization of the payments user interface

20. If detailsPromise was passed, then:
    1. Run the update a PaymentRequest's details algorithm with detailsPromise, request, and null.
    2. Wait for the detailsPromise to settle.

       Note

       Based on how the detailsPromise settles, the update a PaymentRequest's details algorithm determines how the payment UI behaves. That is, upon rejection of the detailsPromise, the payment request aborts. Otherwise, upon fulfillment detailsPromise, the user agent re-enables the payment request UI and the payment flow can continue.

21. Set request.[[handler]] be the payment handler selected by the end-user.
22. Let modifiers be an empty list.
23. For each tuple in [[serializedModifierData]]:
    1. If the first element of tuple (a PMI) matches the payment method identifier of request.[[handler]], then append the second element of tuple (the serialized method data) to modifiers.

24. Pass the converted second element in the paymentMethod tuple and modifiers. Optionally, the user agent SHOULD send the appropriate data from request to the user-selected payment handler in order to guide the user through the payment process. This includes the various attributes and other internal slots of request (some MAY be excluded for privacy reasons where appropriate).

    Handling of multiple applicable modifiers in the [[serializedModifierData]] internal slot is payment handler specific and beyond the scope of this specification. Nevertheless, it is RECOMMENDED that payment handlers use a "last one wins" approach with items in the [[serializedModifierData]] list: that is to say, an item at the end of the list always takes precedence over any item at the beginning of the list (see example below).

    The acceptPromise will later be resolved or rejected by either the user accepts the payment request algorithm or the user aborts the payment request algorithm, which are triggered through interaction with the user interface.

    If document stops being fully active while the user interface is being shown, or no longer is by the time this step is reached, then:

    1. Close down the user interface.
    2. Set request's payment-relevant browsing context's payment request is showing boolean to false.

The abort() method MUST act as follows:

1. Let request be this.
2. If request.[[response]] is not null, and request.[[response]].[[retryPromise]] is not null, return a promise rejected with an "InvalidStateError" DOMException.
3. If the value of request.[[state]] is not "interactive" then return a promise rejected with an "InvalidStateError" DOMException.
4. Let promise be a new promise.
5. Return promise and perform the remaining steps in parallel.
6. Try to abort the current user interaction with the payment handler and close down any remaining user interface.
7. Queue a task on the user interaction task source to perform the following steps:
   1. If it is not possible to abort the current user interaction, then reject promise with "InvalidStateError" DOMException and abort these steps.
   2. Set request.[[state]] to "closed".
   3. Reject the promise request.[[acceptPromise]] with an "AbortError" DOMException.
   4. Resolve promise with undefined.

The canMakePayment() method MUST run the can make payment algorithm.

A PaymentRequest's shippingAddress attribute is populated when the user provides a shipping address. It is null by default. When a user provides a shipping address, the shipping address changed algorithm runs.

A PaymentRequest's shippingType attribute is the type of shipping used to fulfill the transaction. Its value is either a PaymentShippingType enum value, or null if none is provided by the developer during construction (see PaymentOptions's shippingType member).

A PaymentRequest's onshippingaddresschange attribute is an EventHandler for a PaymentRequestUpdateEvent named shippingaddresschange.

A PaymentRequest's shippingOption attribute is populated when the user chooses a shipping option. It is null by default. When a user chooses a shipping option, the shipping option changed algorithm runs.

A PaymentRequest's onshippingoptionchange attribute is an EventHandler for a PaymentRequestUpdateEvent named shippingoptionchange.

A PaymentRequest's onpaymentmethodchange attribute is an EventHandler for a PaymentMethodChangeEvent named "paymentmethodchange".

Instances of PaymentRequest are created with the internal slots in the following table:

Internal Slot	Description (non-normative)
[[serializedMethodData]]	The methodData supplied to the constructor, but represented as tuples containing supported methods and a string or null for data (instead of the original object form).
[[serializedModifierData]]	A list containing the serialized string form of each data member for each corresponding item in the sequence [[details]].modifier, or null if no such member was present.
[[details]]	The current PaymentDetailsBase for the payment request initially supplied to the constructor and then updated with calls to updateWith(). Note that all data members of PaymentDetailsModifier instances contained in the modifiers member will be removed, as they are instead stored in serialized form in the [[serializedModifierData]] internal slot.
[[options]]	The PaymentOptions supplied to the constructor.
[[state]]	The current state of the payment request, which transitions from: "created" The payment request is constructed and has not been presented to the user. "interactive" The payment request is being presented to the user. "closed" The payment request completed. The state transitions are illustrated in the figure below:
[[updating]]	True if there is a pending updateWith() call to update the payment request and false otherwise.
[[acceptPromise]]	The pending Promise created during show() that will be resolved if the user accepts the payment request.
[[response]]	Null, or the PaymentResponse instantiated by this PaymentRequest.
[[handler]]	The Payment Handler associated with this PaymentRequest. Initialized to null.

A JavaScript string is a valid decimal monetary value if it consists of the following code points in the given order:

1. Optionally, a single U+002D (-), to indicate that the amount is negative.
2. One or more code points in the range U+0030 (0) to U+0039 (9).
3. Optionally, a single U+002E (.) followed by one or more code points in the range U+0030 (0) to U+0039 (9).

^-?[0-9]+(\.[0-9]+)?$

To check and canonicalize amount given a PaymentCurrencyAmount amount, run the following steps:

1. If the result of IsWellFormedCurrencyCode(amount.currency) is false, then throw a RangeError exception, optionally informing the developer that the currency is invalid.
2. If amount.value is not a valid decimal monetary value, throw a TypeError, optionally informing the developer that the currency is invalid.
3. Set amount.currency to the result of ASCII uppercase amount.currency.

To check and canonicalize total amount given a PaymentCurrencyAmount amount, run the following steps:

1. Check and canonicalize amount amount. Rethrow any exceptions.
2. If the first code point of amount.value is U+002D (-), then throw a TypeError optionally informing the developer that a total's value can't be a negative number.

dictionary PaymentDetailsBase {
  sequence<PaymentItem> displayItems;
  sequence<PaymentShippingOption> shippingOptions;
  sequence<PaymentDetailsModifier> modifiers;
};

displayItems member

A sequence of PaymentItem dictionaries contains line items for the payment request that the user agent MAY display.

shippingOptions member

A sequence containing the different shipping options for the user to choose from.

If an item in the sequence has the selected member set to true, then this is the shipping option that will be used by default and shippingOption will be set to the id of this option without running the shipping option changed algorithm. If more than one item in the sequence has selected set to true, then the user agent selects the last one in the sequence.

The shippingOptions member is only used if the PaymentRequest was constructed with PaymentOptions and requestShipping set to true.

modifiers member

A sequence of PaymentDetailsModifier dictionaries that contains modifiers for particular payment method identifiers. For example, it allows you to adjust the total amount based on payment method.

dictionary PaymentDetailsInit : PaymentDetailsBase {
  DOMString id;
  required PaymentItem total;
};

In addition to the members inherited from the PaymentDetailsBase dictionary, the following members are part of the PaymentDetailsInit dictionary:

id member

A free-form identifier for this payment request.

total member

A PaymentItem containing a non-negative total amount for the payment request.

dictionary PaymentDetailsUpdate : PaymentDetailsBase {
  DOMString error;
  PaymentItem total;
  AddressErrors shippingAddressErrors;
  PayerErrors payerErrors;
  object paymentMethodErrors;
};

The PaymentDetailsUpdate dictionary is used to update the payment request using updateWith().

In addition to the members inherited from the PaymentDetailsBase dictionary, the following members are part of the PaymentDetailsUpdate dictionary:

error member

A human-readable string that explains why goods cannot be shipped to the chosen shipping address, or any other reason why no shipping options are available. When the payment request is updated using updateWith(), the PaymentDetailsUpdate can contain a message in the error member that will be displayed to the user if the PaymentDetailsUpdate indicates that there are no valid shippingOptions (and the PaymentRequest was constructed with the requestShipping option set to true).

total member

A PaymentItem containing a non-negative amount.

Note

Algorithms in this specification that accept a PaymentDetailsUpdate dictionary will throw if the total.amount.value is a negative number.

shippingAddressErrors member

Represents validation errors with the shipping address that is associated with the potential event target.

payerErrors member

Validation errors related to the payer details.

paymentMethodErrors member

Payment method specific errors.

The retry(errorFields) method MUST act as follows:

1. Let response be this.
2. Let request be response.[[request]].
3. Let document be request's relevant global object's associated Document.
4. If document is not fully active, then return a promise rejected with an "AbortError" DOMException.
5. If response.[[complete]] is true, return a promise rejected with an "InvalidStateError" DOMException.
6. If response.[[retryPromise]] is not null, return a promise rejected with an "InvalidStateError" DOMException.
7. Set request.[[state]] to "interactive".
8. Let retryPromise be a new promise.
9. Set response.[[retryPromise]] to retryPromise.
10. If errorFields was passed:
    1. Optionally, show a warning in the developer console if any of the following are true:
       1. request.[[options]].requestPayerName is false, and errorFields.payer.name is present.
       2. request.[[options]].requestPayerEmail is false, and errorFields.payer.email is present.
       3. request.[[options]].requestPayerPhone is false, and errorFields.payer.phone is present.
       4. request.[[options]].requestShipping is false, and errorFields.shippingAddress is present.
    2. If errorFields.paymentMethod member was passed, and if required by the specification that defines response.methodName, then convert errorFields's paymentMethod member to an IDL value of the type specified there. Otherwise, convert to object.
    3. Set request's payment-relevant browsing context's payment request is showing boolean to false.
    4. If conversion results in a exception error:
       1. Reject retryPromise with error.
       2. Set user agent's payment request is showing boolean to false.
       3. Return.
    5. By matching the members of errorFields to input fields in the user agent's UI, indicate to the end user that something is wrong with the data of the payment response. For example, a user agent might draw the user's attention to the erroneous errorFields in the browser's UI and display the value of each field in a manner that helps the user fix each error. Similarly, if the error member is passed, present the error in the user agent's UI. In the case where the value of a member is the empty string, the user agent MAY substitute a value with a suitable error message.
11. Otherwise, if errorFields was not passed, signal to the end user to attempt to retry the payment. Re-enable any UI element that affords the end user the ability to retry accepting the payment request.
12. If document stops being fully active while the user interface is being shown, or no longer is by the time this step is reached, then:
    1. Close down the user interface.
    2. Set request's payment-relevant browsing context's payment request is showing boolean to false.
13. Finally, when retryPromise settles, set response.[[retryPromise]] to null.
14. Return retryPromise.

    Note

    The retryPromise will later be resolved by the user accepts the payment request algorithm, or rejected by either the user aborts the payment request algorithm or abort the update.

dictionary PaymentValidationErrors {
  PayerErrors payer;
  AddressErrors shippingAddress;
  DOMString error;
  object paymentMethod;
};

dictionary PayerErrors {
  DOMString email;
  DOMString name;
  DOMString phone;
};

The payment method identifier for the payment method that the user selected to fulfill the transaction.

An object or dictionary generated by a payment method that a merchant can use to process or validate a transaction (depending on the payment method).

If the requestShipping member was set to true in the PaymentOptions passed to the PaymentRequest constructor, then shippingAddress will be the full and final shipping address chosen by the user.

If the requestShipping member was set to true in the PaymentOptions passed to the PaymentRequest constructor, then shippingOption will be the id attribute of the selected shipping option.

If the requestPayerName member was set to true in the PaymentOptions passed to the PaymentRequest constructor, then payerName will be the name provided by the user.

If the requestPayerEmail member was set to true in the PaymentOptions passed to the PaymentRequest constructor, then payerEmail will be the email address chosen by the user.

If the requestPayerPhone member was set to true in the PaymentOptions passed to the PaymentRequest constructor, then payerPhone will be the phone number chosen by the user.

The corresponding payment request id that spawned this payment response.

After the payment request has been accepted and the PaymentResponse returned to the caller, but before the caller calls complete(), the payment request user interface remains in a pending state. At this point the user interface SHOULD NOT offer a cancel command because acceptance of the payment request has been returned. However, if something goes wrong and the developer never calls complete() then the user interface is blocked.

For this reason, implementations MAY impose a timeout for developers to call complete(). If the timeout expires then the implementation will behave as if complete() was called with no arguments.

The complete() method MUST act as follows:

1. Let response be this.
2. If response.[[complete]] is true, return a promise rejected with an "InvalidStateError" DOMException.
3. If response.[[retryPromise]] is not null, return a promise rejected with an "InvalidStateError" DOMException.
4. Let promise be a new promise.
5. Let serializedData be the result of serialize details.data into a JSON string.
6. If serializing throws an exception, return a promise rejected with that exception.
7. If required by the specification that defines the response.methodName:
   1. Let json be the result of calling JSON's parse() with serializedData.
   2. Let idl be the result of converting json to an IDL value of the type specified by the specification that defines the response.methodName.
   3. If the conversion to an IDL value throws an exception, return a promise rejected with that exception.
   4. If required by the specification that defines the response.methodName, validate the members of idl. If a member's value is invalid, return a promise rejected with a TypeError.

      Note: Opportunity to recover

8. Set response.[[complete]] to true.
9. Return promise and perform the remaining steps in parallel.
10. If document stops being fully active while the user interface is being shown, or no longer is by the time this step is reached, then:
    1. Close down the user interface.
    2. Set request's payment-relevant browsing context's payment request is showing boolean to false.
11. Otherwise:
    1. Close down any remaining user interface. The user agent MAY use the value result and serializedData to influence the user experience.
    2. Set request's payment-relevant browsing context's payment request is showing boolean to false.
    3. Resolve promise with undefined.

Allows a developer to handle "payerdetailchange" events.

Instances of PaymentResponse are created with the internal slots in the following table:

dictionary AddressErrors {
  DOMString addressLine;
  DOMString city;
  DOMString country;
  DOMString dependentLocality;
  DOMString organization;
  DOMString phone;
  DOMString postalCode;
  DOMString recipient;
  DOMString region;
  DOMString sortingCode;
};

The members of the AddressErrors dictionary represent validation errors with specific parts of a physical address. Each dictionary member has a dual function: firstly, its presence denotes that a particular part of an address is suffering from a validation error. Secondly, the string value allows the developer to describe the validation error (and possibly how the end user can fix the error).

addressLine member

Denotes that the address line has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's addressLine attribute's value.

city member

Denotes that the city has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's city attribute's value.

country member

Denotes that the country has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's country attribute's value.

dependentLocality member

Denotes that the dependent locality has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's dependentLocality attribute's value.

organization member

Denotes that the organization has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's organization attribute's value.

phone member

Denotes that the phone number has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's phone attribute's value.

postalCode member

Denotes that the postal code has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's postalCode attribute's value.

recipient member

Denotes that the recipient has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's addressLine attribute's value.

region member

Denotes that the region has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's region attribute's value.

sortingCode member

The sorting code has a validation error. In the user agent's UI, this member corresponds to the input field that provided the ContactAddress's sortingCode attribute's value.

This section is non-normative.

[SecureContext, Exposed=Window]
interface PaymentMethodChangeEvent : PaymentRequestUpdateEvent {
  constructor(DOMString type, optional PaymentMethodChangeEventInit eventInitDict = {});
  readonly attribute DOMString methodName;
  readonly attribute object? methodDetails;
};

dictionary PaymentMethodChangeEventInit : PaymentRequestUpdateEventInit {
  DOMString methodName = "";
  object? methodDetails = null;
};

[SecureContext, Exposed=Window]
interface PaymentRequestUpdateEvent : Event {
  constructor(DOMString type, optional PaymentRequestUpdateEventInit eventInitDict = {});
  undefined updateWith(Promise<PaymentDetailsUpdate> detailsPromise);
};

The PaymentRequestUpdateEvent enables developers to update the details of the payment request in response to a user interaction.

dictionary PaymentRequestUpdateEventInit : EventInit {};

The can make payment algorithm checks if the user agent supports making payment with the payment methods with which the PaymentRequest was constructed.

1. Let request be the PaymentRequest object on which the method was called.
2. If request.[[state]] is not "created", then return a promise rejected with an "InvalidStateError" DOMException.
3. Optionally, at the top-level browsing context's discretion, return a promise rejected with a "NotAllowedError" DOMException.

   Note

   This allows user agents to apply heuristics to detect and prevent abuse of the calling method for fingerprinting purposes, such as creating PaymentRequest objects with a variety of supported payment methods and triggering the can make payment algorithm on them one after the other. For example, a user agent may restrict the number of successful calls that can be made based on the top-level browsing context or the time period in which those calls were made.

4. Let hasHandlerPromise be a new promise.
5. Return hasHandlerPromise, and perform the remaining steps in parallel.
6. For each paymentMethod tuple in request. [[serializedMethodData]]:
   1. Let identifier be the first element in the paymentMethod tuple.
   2. If the user agent has a payment handler that supports handling payment requests for identifier, resolve hasHandlerPromise with true and terminate this algorithm.
7. Resolve hasHandlerPromise with false.

The shipping address changed algorithm runs when the user provides a new shipping address. It MUST run the following steps:

1. Let request be the PaymentRequest object that the user is interacting with.
2. Queue a task on the user interaction task source to run the following steps:

   1. Note: Privacy of recipient information

      The redactList limits the amount of personal information about the recipient that the API shares with the merchant.

      For merchants, the resulting ContactAddress object provides enough information to, for example, calculate shipping costs, but, in most cases, not enough information to physically locate and uniquely identify the recipient.

      Unfortunately, even with the redactList, recipient anonymity cannot be assured. This is because in some countries postal codes are so fine-grained that they can uniquely identify a recipient.

   2. Let redactList be the empty list. Set redactList to « "organization", "phone", "recipient", "addressLine" ».
   3. Let address be the result of running the steps to create a contactaddress from user-provided input with redactList.
   4. Set request.shippingAddress to address.
   5. Run the PaymentRequest updated algorithm with request and "shippingaddresschange".

The shipping option changed algorithm runs when the user chooses a new shipping option. It MUST run the following steps:

1. Let request be the PaymentRequest object that the user is interacting with.
2. Queue a task on the user interaction task source to run the following steps:
   1. Set the shippingOption attribute on request to the id string of the PaymentShippingOption provided by the user.
   2. Run the PaymentRequest updated algorithm with request and "shippingoptionchange".

A payment handler MAY run the payment method changed algorithm when the user changes payment method with methodDetails, which is a dictionary or an object or null, and a methodName, which is a DOMString that represents the payment method identifier of the payment handler the user is interacting with.

1. Let request be the PaymentRequest object that the user is interacting with.
2. Queue a task on the user interaction task source to run the following steps:
   1. Assert: request.[[updating]] is false. Only one update can take place at a time.
   2. Assert: request.[[state]] is "interactive".
   3. Fire an event named "paymentmethodchange" at request using PaymentMethodChangeEvent, with its methodName attribute initialized to methodName, and its methodDetails attribute initialized to methodDetails.

The PaymentRequest updated algorithm is run by other algorithms above to fire an event to indicate that a user has made a change to a PaymentRequest called request with an event name of name:

1. Assert: request.[[updating]] is false. Only one update can take place at a time.
2. Assert: request.[[state]] is "interactive".
3. Let event be the result of creating an event using the PaymentRequestUpdateEvent interface.
4. Initialize event's type attribute to name.
5. Dispatch event at request.
6. If event.[[waitForUpdate]] is true, disable any part of the user interface that could cause another update event to be fired.
7. Otherwise, set event.[[waitForUpdate]] to true.

The user agent MUST run the payer detail changed algorithm when the user changes the payer name, or the payer email, or the payer phone in the user interface:

1. Let request be the PaymentRequest object that the user is interacting with.
2. If request.[[response]] is null, return.
3. Let response be request.[[response]].
4. Queue a task on the user interaction task source to run the following steps:
   1. Assert: request.[[updating]] is false.
   2. Assert: request.[[state]] is "interactive".
   3. Let options be request.[[options]].
   4. If payer name changed and options.requestPayerName is true:
      1. Set response.payerName attribute to payer name.
   5. If payer email changed and options.requestPayerEmail is true:
      1. Set response.payerEmail to payer email.
   6. If payer phone changed and options.requestPayerPhone is true:
      1. Set response.payerPhone to payer phone.
   7. Let event be the result of creating an event using PaymentRequestUpdateEvent.
   8. Initialize event's type attribute to "payerdetailchange".
   9. Dispatch event at response.
   10. If event.[[waitForUpdate]] is true, disable any part of the user interface that could cause another change to the payer details to be fired.
   11. Otherwise, set event.[[waitForUpdate]] to true.

The user accepts the payment request algorithm runs when the user accepts the payment request and confirms that they want to pay. It MUST queue a task on the user interaction task source to perform the following steps:

1. Let request be the PaymentRequest object that the user is interacting with.
2. If the request.[[updating]] is true, then terminate this algorithm and take no further action. The user agent user interface SHOULD ensure that this never occurs.
3. If request.[[state]] is not "interactive", then terminate this algorithm and take no further action. The user agent user interface SHOULD ensure that this never occurs.
4. If the requestShipping value of request.[[options]] is true, then if the shippingAddress attribute of request is null or if the shippingOption attribute of request is null, then terminate this algorithm and take no further action. The user agent SHOULD ensure that this never occurs.
5. Let isRetry be true if request.[[response]] is not null, false otherwise.
6. Let response be request.[[response]] if isRetry is true, or a new PaymentResponse otherwise.
7. If isRetry is false, initialize the newly created response:
   1. Set response.[[request]] to request.
   2. Set response.[[retryPromise]] to null.
   3. Set response.[[complete]] to false.
   4. Set the requestId attribute value of response to the value of request.[[details]].id.
   5. Set request.[[response]] to response.
8. Let handler be request.[[handler]].
9. Set the methodName attribute value of response to the payment method identifier of handler.
10. Set the details attribute value of response to an object resulting from running the handler's steps to respond to a payment request.
11. If the requestShipping value of request.[[options]] is false, then set the shippingAddress attribute value of response to null. Otherwise:
    1. Let shippingAddress be the result of create a contactaddress from user-provided input
    2. Set the shippingAddress attribute value of response to shippingAddress.
    3. Set the shippingAddress attribute value of request to shippingAddress.
12. If the requestShipping value of request.[[options]] is true, then set the shippingOption attribute of response to the value of the shippingOption attribute of request. Otherwise, set it to null.
13. If the requestPayerName value of request.[[options]] is true, then set the payerName attribute of response to the payer's name provided by the user, or to null if none was provided. Otherwise, set it to null.
14. If the requestPayerEmail value of request.[[options]] is true, then set the payerEmail attribute of response to the payer's email address provided by the user, or to null if none was provided. Otherwise, set it to null.
15. If the requestPayerPhone value of request.[[options]] is true, then set the payerPhone attribute of response to the payer's phone number provided by the user, or to null if none was provided. When setting the payerPhone value, the user agent SHOULD format the phone number to adhere to [E.164].
16. Set request.[[state]] to "closed".
17. If isRetry is true, resolve response.[[retryPromise]] with undefined. Otherwise, resolve request.[[acceptPromise]] with response.

The user aborts the payment request algorithm runs when the user aborts the payment request through the currently interactive user interface. It MUST queue a task on the user interaction task source to perform the following steps:

1. Let request be the PaymentRequest object that the user is interacting with.
2. If request.[[state]] is not "interactive", then terminate this algorithm and take no further action. The user agent user interface SHOULD ensure that this never occurs.
3. Set request.[[state]] to "closed".
4. Set request's payment-relevant browsing context's payment request is showing boolean to false.
5. Let error be an "AbortError" DOMException.
6. Let response be request.[[response]].
7. If response is not null:
   1. Set response.[[complete]] to true.
   2. Assert: response.[[retryPromise]] is not null.
   3. Reject response.[[retryPromise]] with error.
8. Otherwise, reject request.[[acceptPromise]] with error.
9. Abort the current user interaction and close down any remaining user interface.

The update a PaymentRequest's details algorithm takes a PaymentDetailsUpdate detailsPromise, a PaymentRequest request, and pmi that is either a DOMString or null (a payment method identifier). The steps are conditional on the detailsPromise settling. If detailsPromise never settles then the payment request is blocked. The user agent SHOULD provide the user with a means to abort a payment request. Implementations MAY choose to implement a timeout for pending updates if detailsPromise doesn't settle in a reasonable amount of time.

In the case where a timeout occurs, or the user manually aborts, or the payment handler decides to abort this particular payment, the user agent MUST run the user aborts the payment request algorithm.

1. Set request.[[updating]] to true.
2. In parallel, disable the user interface that allows the user to accept the payment request. This is to ensure that the payment is not accepted until the user interface is updated with any new details.
3. Upon rejection of detailsPromise:
   1. Abort the update with request and an "AbortError" DOMException.
4. Upon fulfillment of detailsPromise with value value:
   1. Let details be the result of converting value to a PaymentDetailsUpdate dictionary. If this throw an exception, abort the update with request and with the thrown exception.
   2. Let serializedModifierData be an empty list.
   3. Let selectedShippingOption be null.
   4. Let shippingOptions be an empty sequence<PaymentShippingOption>.
   5. Validate and canonicalize the details:
      1. If the total member of details is present, then:
         1. Check and canonicalize total amount details.total.amount. If an exception is thrown, then abort the update with request and that exception.
      2. If the displayItems member of details is present, then for each item in details.displayItems:
         1. Check and canonicalize amount item.amount. If an exception is thrown, then abort the update with request and that exception.
      3. If the shippingOptions member of details is present, and request.[[options]].requestShipping is true, then:
         1. Let seenIDs be an empty set.
         2. For each option in details.shippingOptions:
            1. Check and canonicalize amount option.amount. If an exception is thrown, then abort the update with request and that exception.
            2. If seenIDs[option.{{PaymentShippingOption/id}] exists, then abort the update with request and a TypeError.
            3. Append option.id to seenIDs.
            4. Append option to shippingOptions.
            5. If option.selected is true, then set selectedShippingOption to option.id.
      4. If the modifiers member of details is present, then:
         1. Let modifiers be the sequence details.modifiers.
         2. Let serializedModifierData be an empty list.
         3. For each PaymentDetailsModifier modifier in modifiers:
            1. Run the steps to validate a payment method identifier with modifier.supportedMethods. If it returns false, then abort the update with request and a RangeError exception. Optionally, inform the developer that the payment method identifier is invalid.
            2. If the total member of modifier is present, then:
               1. Check and canonicalize total amount modifier.total.amount. If an exception is thrown, then abort the update with request and that exception.
            3. If the additionalDisplayItems member of modifier is present, then for each PaymentItem item in modifier.additionalDisplayItems:
               1. Check and canonicalize amount item.amount. If an exception is thrown, then abort the update with request and that exception.
            4. If the data member of modifier is missing, let serializedData be null. Otherwise, let serializedData be the result of serialize modifier.data into a JSON string. If it throws an exception, then abort the update with request and that exception.
            5. Add serializedData to serializedModifierData.
            6. Remove the data member of modifier, if it is present.
   6. If the paymentMethodErrors member is present and identifier is not null:
      1. If required by the specification that defines the pmi, then convert paymentMethodErrors to an IDL value.
      2. If conversion results in a exception error, abort the update with error.
      3. The payment handler SHOULD display an error for each relevant erroneous field of paymentMethodErrors.
   7. Update the PaymentRequest using the new details:
      1. If the total member of details is present, then:
         1. Set request.[[details]].total to details.total.
      2. If the displayItems member of details is present, then:
         1. Set request.[[details]].displayItems to details.displayItems.
      3. If the shippingOptions member of details is present, and request.[[options]].requestShipping is true, then:
         1. Set request.[[details]].shippingOptions to shippingOptions.
         2. Set the value of request's shippingOption attribute to selectedShippingOption.
      4. If the modifiers member of details is present, then:
         1. Set request.[[details]].modifiers to details.modifiers.
         2. Set request.[[serializedModifierData]] to serializedModifierData.

      5. If request.[[options]].requestShipping is true, and request.[[details]].shippingOptions is empty, then the developer has signified that there are no valid shipping options for the currently-chosen shipping address (given by request's shippingAddress).

         In this case, the user agent SHOULD display an error indicating this, and MAY indicate that the currently-chosen shipping address is invalid in some way. The user agent SHOULD use the error member of details, if it is present, to give more information about why there are no valid shipping options for that address.

         Further, if details["shippingAddressErrors"] member is present, the user agent SHOULD display an error specifically for each erroneous field of the shipping address. This is done by matching each present member of the AddressErrors to a corresponding input field in the shown user interface.

         Similarly, if details["payerErrors"] member is present and request.[[options]]'s requestPayerName, requestPayerEmail, or requestPayerPhone is true, then display an error specifically for each erroneous field.

         Likewise, if details.paymentMethodErrors is present, then display errors specifically for each erroneous input field for the particular payment method.

5. Set request.[[updating]] to false.
6. Update the user interface based on any changed values in request. Re-enable user interface elements disabled prior to running this algorithm.

This section is non-normative.

To help ensure that users do not inadvertently share sensitive credentials with an origin, this API requires that PaymentRequest's show() method be invoked while the relevant Window has transient activation (e.g., via a click or press).

To avoid a confusing user experience, this specification limits the user agent to displaying one at a time via the show() method. In addition, the user agent can limit the rate at which a page can call show().

This section is non-normative.

The API defined in this specification is only exposed in a secure context - see also the Secure Contexts specification for more details. In practice, this means that this API is only available over HTTPS. This is to limit the possibility of payment method data (e.g., credit card numbers) being sent in the clear.

This section is non-normative.

It is common for merchants and other payees to delegate checkout and other e-commerce activities to payment service providers through an iframe. This API supports payee-authorized cross-origin iframes through [HTML]'s allow attribute.

Payment handlers have access to both the origin that hosts the iframe and the origin of the iframe content (where the PaymentRequest initiates).

This section is non-normative.

The PaymentRequest API does not directly support encryption of data fields. Individual payment methods may choose to include support for encrypted data but it is not mandatory that all payment methods support this.

This section is non-normative.

For security reasons, a user agent can limit matching (in show() and canMakePayment()) to payment handlers from the same origin as a URL payment method identifier.

Payment method owners establish the privacy policies for how user data collected for the payment method may be used. Payment Request API sets a clear expectation that data will be used for the purposes of completing a transaction, and user experiences associated with this API convey that intention. It is the responsibility of the payee to ensure that any data usage conforms to payment method policies. For any permitted usage beyond completion of the transaction, the payee should clearly communicate that usage to the user.

The user agent MUST NOT share information about the user with a developer (e.g., the shipping address) without user consent.

In particular, the PaymentMethodData's data and PaymentResponse's details members allow for the arbitrary exchange of data. In light of the wide range of data models used by existing payment methods, prescribing data specifics in this API would limit its usefulness. The details member carries data from the payment handler, whether Web-based (as defined by the Payment Handler API) or proprietary. The user agent MUST NOT support payment handlers unless they include adequate user consent mechanisms (such as awareness of parties to the transaction and mechanisms for demonstrating the intention to share data).

The user agent MUST NOT share the values of the displayItems member or additionalDisplayItems member for any purpose other than to facilitate completion of the transaction.

The PaymentMethodChangeEvent enables the payee to update the displayed total based on information specific to a selected payment method. For example, the billing address associated with a selected payment method might affect the tax computation (e.g., VAT), and it is desirable that the user interface accurately display the total before the payer completes the transaction. At the same time, it is desirable to share as little information as possible prior to completion of the payment. Therefore, when a payment method defines the steps for when a user changes payment method, it is important to minimize the data shared via the PaymentMethodChangeEvent's methodDetails attribute. Requirements and approaches for minimizing shared data are likely to vary by payment method and might include:

• Use of a "redactList" for physical addresses. The current specification makes use of a "redactList" to redact the address line, organization, phone number, and recipient from a shippingAddress.
• Support for instructions from the payee identifying specific elements to exclude or include from the payment method response data (returned through PaymentResponse.details). The payee might provide these instructions via PaymentMethodData.data, enabling a payment method definition to evolve without requiring changes to the current API.

Where sharing of privacy-sensitive information might not be obvious to users (e.g., when changing payment methods), it is RECOMMENDED that user agents inform the user of exactly what information is being shared with a merchant.

The canMakePayment() method provides feature detection for different payment methods. It may become a fingerprinting vector if in the future, a large number of payment methods are available. User agents are expected to protect the user from abuse of the method. For example, user agents can reduce user fingerprinting by:

• Rate-limiting the frequency of calls with different parameters.

For rate-limiting the user agent might look at repeated calls from:

• the same registrable domain.
• the top-level browsing context. Alternatively, the user agent may block access to the API entirely for origins known to be bad actors.
• the origin of an iframe or popup window.

These rate-limiting techniques intend to increase the cost associated with repeated calls, whether it is the cost of managing multiple registrable domains or the user experience friction of opening multiple windows (tabs or pop-ups).

If the user agent does not require user activation as part of the show() method, some additional security mitigations should be considered. Not requiring user activation increases the risk of spam and click-jacking attacks, by allowing a Payment Request UI to be initiated without the user interacting with the page immediately beforehand.

In order to mitigate spam, the user agent may decide to enforce a user activation requirement after some threshold, for example after the user has already been shown a Payment Request UI without a user activation on the current page. In order to mitigate click-jacking attacks, the user agent may implement a time threshold in which clicks are ignored immediately after a dialog is shown.

Another relevant mitigation exists in step 6 of show(), where the document must be visible in order to initiate the user interaction.

[contact-picker]

Contact Picker API. Peter Beverloo. W3C. 8 July 2024. W3C Working Draft. URL: https://www.w3.org/TR/contact-picker/

[dom]

DOM Standard. Anne van Kesteren. WHATWG. Living Standard. URL: https://dom.spec.whatwg.org/

[E.164]

The international public telecommunication numbering plan. ITU-T. November 2010. Recommendation. URL: https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-E.164-201011-I!!PDF-E&type=items

[ecma-402]

ECMAScript Internationalization API Specification. Ecma International. URL: https://tc39.es/ecma402/

[ECMASCRIPT]

ECMAScript Language Specification. Ecma International. URL: https://tc39.es/ecma262/multipage/

[fetch]

Fetch Standard. Anne van Kesteren. WHATWG. Living Standard. URL: https://fetch.spec.whatwg.org/

[HTML]

HTML Standard. Anne van Kesteren; Domenic Denicola; Dominic Farolino; Ian Hickson; Philip Jägenstedt; Simon Pieters. WHATWG. Living Standard. URL: https://html.spec.whatwg.org/multipage/

[infra]

Infra Standard. Anne van Kesteren; Domenic Denicola. WHATWG. Living Standard. URL: https://infra.spec.whatwg.org/

[ISO4217]

Currency codes - ISO 4217. ISO. 2015. International Standard. URL: http://www.iso.org/iso/home/standards/currency_codes.htm

[payment-handler]

Payment Handler API. Ian Jacobs; Jinho Bang; Stephen McGruer. W3C. 27 September 2025. W3C Working Draft. URL: https://www.w3.org/TR/payment-handler/

[payment-method-id]

Payment Method Identifiers. Marcos Caceres. W3C. 8 September 2022. W3C Recommendation. URL: https://www.w3.org/TR/payment-method-id/

[permissions-policy]

Permissions Policy. Ian Clelland. W3C. 6 August 2025. W3C Working Draft. URL: https://www.w3.org/TR/permissions-policy-1/

[RFC2119]

Key words for use in RFCs to Indicate Requirement Levels. S. Bradner. IETF. March 1997. Best Current Practice. URL: https://www.rfc-editor.org/rfc/rfc2119

[RFC4122]

A Universally Unique IDentifier (UUID) URN Namespace. P. Leach; M. Mealling; R. Salz. IETF. July 2005. Proposed Standard. URL: https://www.rfc-editor.org/rfc/rfc4122

[RFC8174]

Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words. B. Leiba. IETF. May 2017. Best Current Practice. URL: https://www.rfc-editor.org/rfc/rfc8174

[url]

URL Standard. Anne van Kesteren. WHATWG. Living Standard. URL: https://url.spec.whatwg.org/

[WEBIDL]

Web IDL Standard. Edgar Chen; Timothy Gu. WHATWG. Living Standard. URL: https://webidl.spec.whatwg.org/

[rfc6454]

The Web Origin Concept. A. Barth. IETF. December 2011. Proposed Standard. URL: https://www.rfc-editor.org/rfc/rfc6454

[secure-contexts]

Secure Contexts. Mike West. W3C. 10 November 2023. CRD. URL: https://www.w3.org/TR/secure-contexts/