Payment Request API

W3C Candidate Recommendation Draft 09 September 2024

Abstract

This specification standardizes an API to allow merchants (i.e. web sites selling physical or digital goods) to utilize one or more payment methods with minimal integration. User agents (e.g., browsers) facilitate the payment flow between merchant and user.

Status of This Document

This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.

In September 2022 the Web Payments Working Group published a Payment Request Recommendation. Following privacy and internationalization reviews, the Recommendation excluded capabilities related to billing and shipping addresses. However, implementations have continued to support those features interoperably, and so the Working Group has decided to try to re-align the specification with implementations, and re-engage the community on associated issues.

This document is a Candidate Recommendation Snapshot based on the text of the original Recommendation. A subsequent Candidate Recommendation Draft will add back address capabilities and a small number of other changes made since publication of the Recommendation.

As part of adding back support for addresses, this specification now refers to the address components defined in the Contact Picker API rather than define those components itself. Indeed, the Contact Picker API is derived from the original definitions found in Payment Request API, and pulled out of the specification because addresses are useful on the Web beyond payments.

The Working Group plans to engage in discussion and follow the usual review process before advancing the specification to Proposed Recommendation status.

The working group will demonstrate implementation experience by producing an implementation report. The report will show two or more independent implementations passing each mandatory test in the test suite (i.e., each test corresponds to a MUST requirement of the specification).

This document was published by the Web Payments Working Group as a Candidate Recommendation Draft using the Recommendation track.

Publication as a Candidate Recommendation does not imply endorsement by W3C and its Members. A Candidate Recommendation Draft integrates changes from the previous Candidate Recommendation that the Working Group intends to include in a subsequent Candidate Recommendation Snapshot.

This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress. Future updates to this specification may incorporate new features.

This document was produced by a group operating under the W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 03 November 2023 W3C Process Document.

This section is non-normative.

This specification describes an API that allows user agents (e.g., browsers) to act as an intermediary between three parties in a transaction:

The payee: the merchant that runs an online store, or other party that requests to be paid.
The payer: the party that makes a purchase at that online store, and who authenticates and authorizes payment as required.
The payment method: the means that the payer uses to pay the payee (e.g., a card payment or credit transfer). The payment method provider establishes the ecosystem to support that payment method.

A payment method defines:

An optional additional data type: Optionally, an IDL type that the payment method expects to receive as the PaymentMethodData's data member. If not specified for a given payment method, no conversion to IDL is done and the payment method will receive data as JSON.
Steps to validate payment method data: Algorithmic steps that specify how a payment method validates the data member of the PaymentMethodData, after it is converted to the payment method's additional data type. If not specified for a given payment method, no validation is done.

The details of how to fulfill a payment request for a given payment method is an implementation detail of a payment handler, which is an application or service that handles requests for payment. Concretely, a payment handler defines:

Steps to check if a payment can be made:: How a payment handler determines whether it, or the user, can potentially "make a payment" is also an implementation detail of a payment handler.
Steps to respond to a payment request:: Steps that return an object or dictionary that a merchant uses to process or validate the transaction. The structure of this object is specific to each payment method.
Steps for when a user changes payment method (optional): Steps that describe how to handle the user changing payment method or monetary instrument (e.g., from a debit card to a credit card) that results in a dictionary or object or null.

This API also enables web sites to take advantage of more secure payment schemes (e.g., tokenization and system-level authentication) that are not possible with standard JavaScript libraries. This has the potential to reduce liability for the merchant and helps protect sensitive user information.

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.

This section is non-normative.

In order to use the API, the developer needs to provide and keep track of a number of key pieces of information. These bits of information are passed to the PaymentRequest constructor as arguments, and subsequently used to update the payment request being displayed to the user. Namely, these bits of information are:

The methodData: A sequence of PaymentMethodDatas that represents the payment methods that the site supports (e.g., "we support card-based payments, but only Visa and MasterCard credit cards.").
The details: The details of the transaction, as a PaymentDetailsInit dictionary. This includes total cost, and optionally a list of goods or services being purchased, for physical goods, and shipping options. Additionally, it can optionally include "modifiers" to how payments are made. For example, "if you pay with a card belonging to network X, it incurs a US$3.00 processing fee".
The options: Optionally, a list of things as PaymentOptions that the site needs to deliver the good or service (e.g., for physical goods, the merchant will typically need a physical address to ship to. For digital goods, an email will usually suffice).

Once a PaymentRequest is constructed, it's presented to the end user via the show() method. The show() returns a promise that, once the user confirms request for payment, results in a PaymentResponse.

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).

Example 1: The `methodData` argument

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.

Example 2: The `details` argument

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.

Example 3: Adding shipping options

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.

Example 4: Modifying payment request based on card type

// 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.

Example 5: The `options` argument

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:

Example 6: Constructing a `PaymentRequest`

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.

Example 7: Registering event handlers

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.

Example 8

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:

Example 9: POSTing with `fetch()`

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.

Example 10: Using Payment Request API with cross-origin iframes

<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.

WebIDL[SecureContext, Exposed=Window]
interface PaymentRequest : EventTarget {
  constructor(
    sequence<PaymentMethodData> methodData,
    PaymentDetailsInit details,
    optional PaymentOptions options = {}
  );
  [NewObject]
  Promise<PaymentResponse> show(optional Promise<PaymentDetailsUpdate> detailsPromise);
  [NewObject]
  Promise<undefined> abort();
  [NewObject]
  Promise<boolean> canMakePayment();

  readonly attribute DOMString id;
  readonly attribute ContactAddress? shippingAddress;
  readonly attribute DOMString? shippingOption;
  readonly attribute PaymentShippingType? shippingType;

  attribute EventHandler onshippingaddresschange;
  attribute EventHandler onshippingoptionchange;
  attribute EventHandler onpaymentmethodchange;
};

Note

A developer creates a PaymentRequest to make a payment request. This is typically associated with the user initiating a payment process (e.g., by activating a "Buy," "Purchase," or "Checkout" button on a web site, selecting a "Power Up" in an interactive game, or paying at a kiosk in a parking structure). The PaymentRequest allows developers to exchange information with the user agent while the user is providing input (up to the point of user approval or denial of the payment request).

The shippingAddress, shippingOption, and shippingType attributes are populated during processing if the requestShipping member is set.

A request's payment-relevant browsing context is that PaymentRequest's relevant global object's browsing context's top-level browsing context. Every payment-relevant browsing context has a payment request is showing boolean, which prevents showing more than one payment UI at a time.

The payment request is showing boolean simply prevents more than one payment UI being shown in a single browser tab. However, a payment handler can restrict the user agent to showing only one payment UI across all browser windows and tabs. Other payment handlers might allow showing a payment UI across disparate browser tabs.

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:

If this's relevant global object's associated Document is not allowed to use the "payment" permission, then throw a "SecurityError" DOMException.
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].
Let serializedMethodData be an empty list.
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.
Process the total:
1. Check and canonicalize total amount details.total.amount. Rethrow any exceptions.
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.
Let selectedShippingOption be null.
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.
Let serializedModifierData be an empty list.
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.
Let request be a new PaymentRequest.
Set request.[[handler]] to null.
Set request.[[options]] to options.
Set request.[[state]] to "created".
Set request.[[updating]] to false.
Set request.[[details]] to details.
Set request.[[serializedModifierData]] to serializedModifierData.
Set request.[[serializedMethodData]] to serializedMethodData.
Set request.[[response]] to null.
Set the value of request's shippingOption attribute to selectedShippingOption.
Set the value of the shippingAddress attribute on request to null.
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.
Return request.

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

Note

For auditing and reconciliation purposes, a merchant can associate a unique identifier for each transaction with the id attribute.

Note

The show() method is called when a developer wants to begin user interaction for the payment request. The show() method returns a Promise that will be resolved when the user accepts the payment request. Some kind of user interface will be presented to the user to facilitate the payment request after the show() method returns.

Each payment handler controls what happens when multiple browsing context simultaneously call the show() method. For instance, some payment handlers will allow multiple payment UIs to be shown in different browser tabs/windows. Other payment handlers might only allow a single payment UI to be shown for the entire user agent.

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

Let request be this.
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().
Otherwise, consume user activation of the relevant global object.
Let document be request's relevant global object's associated Document.
If document is not fully active, then return a promise rejected with an "AbortError" DOMException.
If document's visibility state is not "visible", then return a promise rejected with an "AbortError" DOMException.
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.
If request.[[state]] is not "created" then return a promise rejected with an "InvalidStateError" DOMException.
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.
Set request.[[state]] to "interactive".
Let acceptPromise be a new promise.
Set request.[[acceptPromise]] to acceptPromise.
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.
Set request's payment-relevant browsing context's payment request is showing boolean to true.
Return acceptPromise and perform the remaining steps in parallel.
Let handlers be an empty list.
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
  Mechanisms to register a payment handler are outside the scope of this specification. For one mechanism, see Payment Handler API.
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.
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.
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

The API does not currently provide a way for developers to specify the language and base direction in which the payment sheet is presented to end users. Instead, the API relies on localization information inherited from the document.
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.
Set request.[[handler]] be the payment handler selected by the end-user.
Let modifiers be an empty list.
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.
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).
Example 11: Handling of multiple applicable modifiers

This example demonstrates precedence order of [[serializedModifierData]]. The first modifier applies equally to all cards, irrespective of network. The second modifier applies specifically to cards on the "coolcard" network.
```
const details = {
  total: {
    label: "Total due",
    amount: { currency: "USD", value: "50.00" },
  },
};
// All cards incur a $3.00 processing fee.
const cardFee = {
  label: "Card processing fee",
  amount: { currency: "USD", value: "3.00" },
};

// But coolcard incurs a $1.00 processing fee.
const coolCardFee = {
  label: "Coolcard processing fee",
  amount: { currency: "USD", value: "1.00" },
};

// Modifiers apply when the user chooses to pay with
// a credit card.
details.modifiers = [
  // Applies to all cards...
  {
    additionalDisplayItems: [cardFee],
    supportedMethods: "https://example.com/cardpay",
    total: {
      label: "Total due",
      amount: { currency: "USD", value: "53.00" },
    },
    data: {
      supportedNetworks: [], // All networks
    },
  },
  // Applies only to cool cards...
  {
    additionalDisplayItems: [coolCardFee],
    supportedMethods: "https://example.com/cardpay",
    total: {
      label: "Total due",
      amount: { currency: "USD", value: "51.00" },
    },
    data: {
      supportedNetworks: ["coolcard"], // coolcard network only
    },
  },
];
```
If the modifiers array in the example above was to be reversed (i.e., supportedNetworks: [] was to come last in the modifiers list), then it would take precedence over the "coolcard" modifier even though the coolcard modifier matches cards more specifically. This is because "last one wins".
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.

Note

The abort() method is called if a developer wishes to tell the user agent to abort the payment request and to tear down any user interface that might be shown. The abort() can only be called after the show() method has been called (see states) and before this instance's [[acceptPromise]] has been resolved. For example, developers might choose to do this if the goods they are selling are only available for a limited amount of time. If the user does not accept the payment request within the allowed time period, then the request will be aborted.

A user agent might not always be able to abort a request. For example, if the user agent has delegated responsibility for the request to another app. In this situation, abort() will reject the returned Promise.

See also the algorithm when the user aborts the payment request.

The abort() method MUST act as follows:

Let request be this.
If request.[[response]] is not null, and request.[[response]].[[retryPromise]] is not null, return a promise rejected with an "InvalidStateError" DOMException.
If the value of request.[[state]] is not "interactive" then return a promise rejected with an "InvalidStateError" DOMException.
Let promise be a new promise.
Return promise and perform the remaining steps in parallel.
Try to abort the current user interaction with the payment handler and close down any remaining user interface.
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.

Note: canMakePayment()

The canMakePayment() method can be used by the developer to determine if the user agent has support for one of the desired payment methods. See 19.8 canMakePayment() protections.

A true result from canMakePayment() does not imply that the user has a provisioned instrument ready for payment.

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: Figure 1 The constructor sets the initial state to "created". The `show()` method changes the state to "interactive". From there, the `abort()` method or any other error can send the state to "closed"; similarly, the user accepts the payment request algorithm and user aborts the payment request algorithm will change the state to "closed".
[[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`.

WebIDLdictionary PaymentMethodData {
  required DOMString supportedMethods;
  object data;
};

A PaymentMethodData dictionary is used to indicate a set of supported payment methods and any associated payment method specific data for those methods.

supportedMethods member: A payment method identifier for a payment method that the merchant web site accepts.
data member: An object that provides optional information that might be needed by the supported payment methods. If supplied, it will be serialized.

Note

The value of supportedMethods was changed from array to string, but the name was left as a plural to maintain compatibility with existing content on the Web.

WebIDLdictionary PaymentCurrencyAmount {
  required DOMString currency;
  required DOMString value;
};

A PaymentCurrencyAmount dictionary is used to supply monetary amounts.

currency member

An [ISO4217] well-formed 3-letter alphabetic code (i.e., the numeric codes are not supported). Their canonical form is upper case. However, the set of combinations of currency code for which localized currency symbols are available is implementation dependent.

When displaying a monetary value, it is RECOMMENDED that user agents display the currency code, but it's OPTIONAL for user agents to display a currency symbol. This is because currency symbols can be ambiguous due to use across a number of different currencies (e.g., "$" could mean any of USD, AUD, NZD, CAD, and so on.).

User agents MAY format the display of the currency member to adhere to OS conventions (e.g., for localization purposes).

Note: Digital currencies and ISO 4217 currency codes

User agents implementing this specification enforce [ISO4217]'s 3-letter codes format via ECMAScript’s isWellFormedCurrencyCode abstract operation, which is invoked as part of the check and canonicalize amount algorithm. When a code does not adhere to the [ISO4217] defined format, a RangeError is thrown.

Current implementations will therefore allow the use of well-formed currency codes that are not part of the official [ISO4217] list (e.g., XBT, XRP, etc.). If the provided code is a currency that the browser knows how to display, then an implementation will generally display the appropriate currency symbol in the user interface (e.g., "USD" is shown as U+0024 Dollar Sign ($), "GBP" is shown as U+00A3 Pound Sign (£), "PLN" is shown as U+007A U+0142 Złoty (zł), and the non-standard "XBT" could be shown as U+0243 Latin Capital Letter B with Stroke (Ƀ)).

Efforts are underway at ISO to account for digital currencies, which may result in an update to the [ISO4217] registry or an entirely new registry. The community expects this will resolve ambiguities that have crept in through the use of non-standard 3-letter codes; for example, does "BTC" refer to Bitcoin or to a future Bhutan currency? At the time of publication, it remains unclear what form this evolution will take, or even the time frame in which the work will be completed. The W3C Web Payments Working Group is liaising with ISO so that, in the future, revisions to this specification remain compatible with relevant ISO registries.

value member

A valid decimal monetary value containing a monetary amount.

Example 12: How to represent 1.234 Omani rials

{
   "currency": "OMR",
   "value": "1.234"
}

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

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

Note

The following regular expression is an implementation of the above definition.

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

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

If the result of IsWellFormedCurrencyCode(amount.currency) is false, then throw a RangeError exception, optionally informing the developer that the currency is invalid.
If amount.value is not a valid decimal monetary value, throw a TypeError, optionally informing the developer that the currency is invalid.
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:

Check and canonicalize amount amount. Rethrow any exceptions.
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.

Note: No alteration of values

WebIDLdictionary 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.

Note

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.

Note

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.

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

Note

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.
Note
If an id member is not present, then the user agent will generate a unique identifier for the payment request during construction
total member: A PaymentItem containing a non-negative total amount for the payment request.
Note
Algorithms in this specification that accept a PaymentDetailsInit dictionary will throw if the total.amount.value is a negative number.

WebIDLdictionary 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.

WebIDLdictionary PaymentDetailsModifier {
  required DOMString supportedMethods;
  PaymentItem total;
  sequence<PaymentItem> additionalDisplayItems;
  object data;
};

The PaymentDetailsModifier dictionary provides details that modify the PaymentDetailsBase based on a payment method identifier. It contains the following members:

supportedMethods member: A payment method identifier. The members of the PaymentDetailsModifier only apply if the user selects this payment method.
total member: A PaymentItem value that overrides the total member in the PaymentDetailsInit dictionary for the payment method identifiers of the supportedMethods member.
additionalDisplayItems member: A sequence of PaymentItem dictionaries provides additional display items that are appended to the displayItems member in the PaymentDetailsBase dictionary for the payment method identifiers in the supportedMethods member. This member is commonly used to add a discount or surcharge line item indicating the reason for the different total amount for the selected payment method that the user agent MAY display.
Note
It is the developer's responsibility to verify that the total amount is the sum of the displayItems and the additionalDisplayItems.
data member: An object that provides optional information that might be needed by the supported payment methods. If supplied, it will be serialized.

WebIDLenum PaymentShippingType {
  "shipping",
  "delivery",
  "pickup"
};

"shipping": This is the default and refers to the address being collected as the destination for shipping.
"delivery": This refers to the address being collected as the destination for delivery. This is commonly faster than shipping. For example, it might be used for food delivery.
"pickup": This refers to the address being collected as part of a service pickup. For example, this could be the address for laundry pickup.

WebIDLdictionary PaymentOptions {
  boolean requestPayerName = false;
  boolean requestBillingAddress = false;
  boolean requestPayerEmail = false;
  boolean requestPayerPhone = false;
  boolean requestShipping = false;
  PaymentShippingType shippingType = "shipping";
};

Note

The PaymentOptions dictionary is passed to the PaymentRequest constructor and provides information about the options desired for the payment request.

requestBillingAddress member: A boolean that indicates whether the user agent SHOULD collect and return the billing address associated with a payment method (e.g., the billing address associated with a credit card). Typically, the user agent will return the billing address as part of the PaymentMethodChangeEvent's methodDetails. A merchant can use this information to, for example, calculate tax in certain jurisdictions and update the displayed total. See below for privacy considerations regarding exposing user information.
requestPayerName member: A boolean that indicates whether the user agent SHOULD collect and return the payer's name as part of the payment request. For example, this would be set to true to allow a merchant to make a booking in the payer's name.
requestPayerEmail member: A boolean that indicates whether the user agent SHOULD collect and return the payer's email address as part of the payment request. For example, this would be set to true to allow a merchant to email a receipt.
requestPayerPhone member: A boolean that indicates whether the user agent SHOULD collect and return the payer's phone number as part of the payment request. For example, this would be set to true to allow a merchant to phone a customer with a billing enquiry.
requestShipping member: A boolean that indicates whether the user agent SHOULD collect and return a shipping address as part of the payment request. For example, this would be set to true when physical goods need to be shipped by the merchant to the user. This would be set to false for the purchase of digital goods.
shippingType member: A PaymentShippingType enum value. Some transactions require an address for delivery but the term "shipping" isn't appropriate. For example, "pizza delivery" not "pizza shipping" and "laundry pickup" not "laundry shipping". If requestShipping is set to true, then the shippingType member can influence the way the user agent presents the user interface for gathering the shipping address.
The shippingType member only affects the user interface for the payment request.

WebIDLdictionary PaymentItem {
  required DOMString label;
  required PaymentCurrencyAmount amount;
  boolean pending = false;
};

A sequence of one or more PaymentItem dictionaries is included in the PaymentDetailsBase dictionary to indicate what the payment request is for and the value asked for.

label member: A human-readable description of the item. The user agent may display this to the user.
Note: Internationalization of the label

The language and direction of the label may often be determined from information inherited from the document. However, this approach may not suffice for some use cases. The working group intends to fix this in a future version by aligning with general approaches for the Web that are in development.
amount member: A PaymentCurrencyAmount containing the monetary amount for the item.
pending member: A boolean. When set to true it means that the amount member is not final. This is commonly used to show items such as shipping or tax amounts that depend upon selection of shipping address or shipping option. User agents MAY indicate pending fields in the user interface for the payment request.

WebIDLdictionary PaymentCompleteDetails {
  object? data = null;
};

The PaymentCompleteDetails dictionary provides additional information from the merchant website to the payment handler when the payment request completes.

The PaymentCompleteDetails dictionary contains the following members:

data member: An object that provides optional information that might be needed by the PaymentResponse associated payment method. If supplied, it will be serialize.

WebIDLenum PaymentComplete {
  "fail",
  "success",
  "unknown"
};

"fail": Indicates that processing of the payment failed. The user agent MAY display UI indicating failure.
"success": Indicates the payment was successfully processed. The user agent MAY display UI indicating success.
"unknown": The developer did not indicate success or failure and the user agent SHOULD NOT display UI indicating success or failure.

WebIDLdictionary PaymentShippingOption {
  required DOMString id;
  required DOMString label;
  required PaymentCurrencyAmount amount;
  boolean selected = false;
};

The PaymentShippingOption dictionary has members describing a shipping option. Developers can provide the user with one or more shipping options by calling the updateWith() method in response to a change event.

id member: A string identifier used to reference this PaymentShippingOption. It MUST be unique for a given PaymentRequest.
label member: A human-readable string description of the item. The user agent SHOULD use this string to display the shipping option to the user.
amount member: A PaymentCurrencyAmount containing the monetary amount for the item.
selected member: A boolean. When true, it indicates that this is the default selected PaymentShippingOption in a sequence. User agents SHOULD display this option by default in the user interface.

WebIDL[SecureContext, Exposed=Window]
interface PaymentResponse : EventTarget  {
  [Default] object toJSON();

  readonly attribute DOMString requestId;
  readonly attribute DOMString methodName;
  readonly attribute object details;
  readonly attribute ContactAddress? shippingAddress;
  readonly attribute DOMString? shippingOption;
  readonly attribute DOMString? payerName;
  readonly attribute DOMString? payerEmail;
  readonly attribute DOMString? payerPhone;

  [NewObject]
  Promise<undefined> complete(
    optional PaymentComplete result = "unknown",
    optional PaymentCompleteDetails details = {}
  );
  [NewObject]
  Promise<undefined> retry(optional PaymentValidationErrors errorFields = {});

  attribute EventHandler onpayerdetailchange;
};

Note

A PaymentResponse is returned when a user has selected a payment method and approved a payment request.

Note

If a PaymentResponse is found to be erroneous (e.g., a payment instrument has expired or shipping information is invalid), the retry() method affords the end user the ability to fix input errors and try to get the merchant to processed the payment again. The passed PaymentValidationErrors serve as hints as to where input errors have occurred in the PaymentResponse, which the end user needs to correct.

However, an end user may decide, upon inspection of the PaymentValidationErrors, to provide an entirely new set of values for the PaymentResponse. For example, the user might switch to a an entirely different payment instrument and/or provide an entirely different shipping address.

As such, merchants need to be prepared to completely revalidate a PaymentResponse once the [[retryPromise]] settles.

Lastly, as a PaymentResponse is inherently tied to a particular payment handler via a PaymentRequest, it is not possible for the end user to switch to a different payment handler during retry().

The retry(errorFields) method MUST act as follows:

Let response be this.
Let request be response.[[request]].
Let document be request's relevant global object's associated Document.
If document is not fully active, then return a promise rejected with an "AbortError" DOMException.
If response.[[complete]] is true, return a promise rejected with an "InvalidStateError" DOMException.
If response.[[retryPromise]] is not null, return a promise rejected with an "InvalidStateError" DOMException.
Set request.[[state]] to "interactive".
Let retryPromise be a new promise.
Set response.[[retryPromise]] to retryPromise.
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.
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.
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.
Finally, when retryPromise settles, set response.[[retryPromise]] to null.
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.

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

payer member: Validation errors related to the payer details.
shippingAddress member: Represents validation errors with the PaymentResponse's shippingAddress.
error member: A general description of an error with the payment from which the user can attempt to recover. For example, the user may recover by retrying the payment. A developer can optionally pass the error member on its own to give a general overview of validation issues, or it can be passed in combination with other members of the PaymentValidationErrors dictionary.
Note: Internationalization of the error

The language and direction of the error may often be determined from information inherited from the document. However, this approach may not suffice for some use cases. The working group intends to fix this in a future version by aligning with general approaches for the Web that are in development.
paymentMethod member: A payment method specific errors.

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

The PayerErrors is used to represent validation errors with one or more payer details.

Payer details are any of the payer's name, payer's phone number, and payer's email.

email member: Denotes that the payer's email suffers from a validation error. In the user agent's UI, this member corresponds to the input field that provided the PaymentResponse's payerEmail attribute's value.
name member: Denotes that the payer's name suffers from a validation error. In the user agent's UI, this member corresponds to the input field that provided the PaymentResponse's payerName attribute's value.
phone member: Denotes that the payer's phone number suffers from a validation error. In the user agent's UI, this member corresponds to the input field that provided the PaymentResponse's payerPhone attribute's value.

Example 13: Payer-related validation errors

const payer = {
  email: "The domain is invalid.",
  phone: "Unknown country code.",
  name: "Not in database.",
};
await response.retry({ payer });

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).

Note

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.

Note

The complete() method is called after the user has accepted the payment request and the [[acceptPromise]] has been resolved. Calling the complete() method tells the user agent that the payment interaction is over (and SHOULD cause any remaining user interface to be closed).

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:

Let response be this.
If response.[[complete]] is true, return a promise rejected with an "InvalidStateError" DOMException.
If response.[[retryPromise]] is not null, return a promise rejected with an "InvalidStateError" DOMException.
Let promise be a new promise.
Let serializedData be the result of serialize details.data into a JSON string.
If serializing throws an exception, return a promise rejected with that exception.
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
  
  The steps above assures that errors that could result from IDL type conversion and/or validation are caught as early as possible, giving the developer an opportunity to recover.
Set response.[[complete]] to true.
Return promise and perform the remaining steps in parallel.
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.
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:

Internal Slot	Description (non-normative)
[[complete]]	Is true if the request for payment has completed (i.e., `complete()` was called, or there was a fatal error that made the response not longer usable), or false otherwise.
[[request]]	The `PaymentRequest` instance that instantiated this `PaymentResponse`.
[[retryPromise]]	Null, or a `Promise` that resolves when a user accepts the payment request or rejects if the user aborts the payment request.

The PaymentRequest interface allows a merchant to request from the user physical addresses for the purposes of shipping and/or billing. A shipping address and billing address are physical addresses.

WebIDLdictionary 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).

Note

Developers need to be aware that users might not have the ability to fix certain parts of an address. As such, they need to be mindful not to ask the user to fix things they might not have control over.

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.

MDN

Headers/Feature-Policy/payment

Chrome	60+
Chrome Android	?
Edge	?
Edge Mobile	?
Firefox	74+
Firefox Android	?
Opera	?
Opera Android	?
Safari	No
Safari iOS	?
Samsung Internet	?
WebView Android	?

MDN🚫

Headers/Permissions-Policy/payment

This feature has limited support.

Chrome	?
Chrome Android	?
Edge	?
Edge Mobile	?
Firefox	74+
Firefox Android	?
Opera	?
Opera Android	?
Safari	No
Safari iOS	?
Samsung Internet	?
WebView Android	?

This specification defines a policy-controlled feature identified by the string "payment" [permissions-policy]. Its default allowlist is 'self'.

Note

This section is non-normative.

Event name	Interface	Dispatched when…	Target
`shippingaddresschange`	`PaymentRequestUpdateEvent`	The user provides a new shipping address.	`PaymentRequest`
`shippingoptionchange`	`PaymentRequestUpdateEvent`	The user chooses a new shipping option.	`PaymentRequest`
`payerdetailchange`	`PaymentRequestUpdateEvent`	The user changes the payer name, the payer email, or the payer phone (see payer detail changed algorithm).	`PaymentResponse`
`paymentmethodchange`	`PaymentMethodChangeEvent`	The user chooses a different payment method within a payment handler.	`PaymentRequest`

MDN✅

PaymentMethodChangeEvent

This feature is in all major engines.

Chrome	76+
Chrome Android	?
Edge	?
Edge Mobile	?
Firefox	55+
Firefox Android	?
Opera	?
Opera Android	?
Safari	12.1+
Safari iOS	?
Samsung Internet	?
WebView Android	No

MDN✅

PaymentMethodChangeEvent/PaymentMethodChangeEvent

This feature is in all major engines.

Chrome	76+
Chrome Android	?
Edge	?
Edge Mobile	?
Firefox	55+
Firefox Android	?
Opera	?
Opera Android	?
Safari	12.1+
Safari iOS	?
Samsung Internet	?
WebView Android	No

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

When getting, returns the value it was initialized with. See methodDetails member of PaymentMethodChangeEventInit for more information.

When getting, returns the value it was initialized with. See methodName member of PaymentMethodChangeEventInit for more information.

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

methodName member: A string representing the payment method identifier.
methodDetails member: An object representing some data from the payment method, or null.

WebIDL[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.

The PaymentRequestUpdateEvent's constructor(type, eventInitDict) MUST act as follows:

Let event be the result of calling the constructor of PaymentRequestUpdateEvent with type and eventInitDict.
Set event.[[waitForUpdate]] to false.
Return event.

Note

If a developer wants to update the payment request, then they need to call updateWith() and provide a PaymentDetailsUpdate dictionary, or a promise for one, containing changed values that the user agent presents to the user.

To prevent the user interface from blocking (and to reflect changes made by the end user through the UI), developers need to immediately call updateWith().

Example: how to use `updateWith()` correctly.

// ❌ Bad - this won't work!
request.onshippingaddresschange = async ev => {
  // await goes to next tick, and updateWith()
  // was not called.
  const details = await getNewDetails(oldDetails);
  // 💥 So it's now too late! updateWith()
  // throws "InvalidStateError".
  ev.updateWith(details);
};

// ✅ Good - UI will wait.
request.onshippingaddresschange = ev => {
  // Calling updateWith() with a promise is ok 👍
  const promiseForNewDetails = getNewDetails(oldDetails);
  ev.updateWith(promiseForNewDetails);
};

Additionally, [[waitForUpdate]] prevents reuse of PaymentRequestUpdateEvent.

Example: can only call `updateWith()` once

// ❌ Bad - calling updateWith() twice doesn't work!
request.addEventListener("shippingaddresschange", ev => {
  ev.updateWith(details); // this is ok.
  // 💥 [[waitForUpdate]] is true, throws "InvalidStateError".
  ev.updateWith(otherDetails);
});

// ❌ Bad - this won't work either!
request.addEventListener("shippingaddresschange", async ev => {
  const p = Promise.resolve({ ...details });
  ev.updateWith(p);
  await p;
  // 💥 Only one call to updateWith() is allowed,
  // so the following throws "InvalidStateError"
  ev.updateWith({ ...newDetails });
});

The updateWith() with detailsPromise method MUST act as follows:

Let event be this.
If event's isTrusted attribute is false, then throw an "InvalidStateError" DOMException.
If event.[[waitForUpdate]] is true, then throw an "InvalidStateError" DOMException.
If event's target is an instance of PaymentResponse, let request be event's target's [[request]].
Otherwise, let request be the value of event's target.
Assert: request is an instance of PaymentRequest.
If request.[[state]] is not "interactive", then throw an "InvalidStateError" DOMException.
If request.[[updating]] is true, then throw an "InvalidStateError" DOMException.
Set event's stop propagation flag and stop immediate propagation flag.
Set event.[[waitForUpdate]] to true.
Let pmi be null.
If event has a methodName attribute, set pmi to the methodName attribute's value.
Run the update a PaymentRequest's details algorithm with detailsPromise, request, and pmi.

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

Internal Slot	Description (non-normative)
[[waitForUpdate]]	A boolean indicating whether an `updateWith()`-initiated update is currently in progress.

WebIDLdictionary PaymentRequestUpdateEventInit : EventInit {};

When the internal slot [[state]] of a PaymentRequest object is set to "interactive", the user agent will trigger the following algorithms based on user interaction.

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

Let request be the PaymentRequest object on which the method was called.
If request.[[state]] is not "created", then return a promise rejected with an "InvalidStateError" DOMException.
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.
Let hasHandlerPromise be a new promise.
Return hasHandlerPromise, and perform the remaining steps in parallel.
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.
Resolve hasHandlerPromise with false.

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

Let request be the PaymentRequest object that the user is interacting with.
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:

Let request be the PaymentRequest object that the user is interacting with.
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.

Note: Privacy of information shared by paymentmethodchange event

When the user selects or changes a payment method (e.g., a credit card), the PaymentMethodChangeEvent includes redacted billing address information for the purpose of performing tax calculations. Redacted attributes include, but are not limited to, address line, dependent locality, organization, phone number, and recipient.

Let request be the PaymentRequest object that the user is interacting with.
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:

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

Let request be the PaymentRequest object that the user is interacting with.
If request.[[response]] is null, return.
Let response be request.[[response]].
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:

Let request be the PaymentRequest object that the user is interacting with.
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.
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.
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.
Let isRetry be true if request.[[response]] is not null, false otherwise.
Let response be request.[[response]] if isRetry is true, or a new PaymentResponse otherwise.
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.
Let handler be request.[[handler]].
Set the methodName attribute value of response to the payment method identifier of handler.
Set the details attribute value of response to an object resulting from running the handler's steps to respond to a payment request.
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.
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.
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.
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.
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].
Set request.[[state]] to "closed".
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:

Let request be the PaymentRequest object that the user is interacting with.
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.
Set request.[[state]] to "closed".
Set request's payment-relevant browsing context's payment request is showing boolean to false.
Let error be an "AbortError" DOMException.
Let response be request.[[response]].
If response is not null:
1. Set response.[[complete]] to true.
2. Assert: response.[[retryPromise]] is not null.
3. Reject response.[[retryPromise]] with error.
Otherwise, reject request.[[acceptPromise]] with error.
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.

Set request.[[updating]] to true.
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.
Upon rejection of detailsPromise:
1. Abort the update with request and an "AbortError" DOMException.
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:
        
        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:
        
        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.
Set request.[[updating]] to false.
Update the user interface based on any changed values in request. Re-enable user interface elements disabled prior to running this algorithm.

To abort the update with a PaymentRequest request and exception exception:

Optionally, show an error message to the user when letting them know an error has occurred.
Abort the current user interaction and close down any remaining user interface.
Queue a task on the user interaction task source to perform the following steps:
1. Set request's payment-relevant browsing context's payment request is showing boolean to false.
2. Set request.[[state]] to "closed".
3. Let response be request.[[response]].
4. If response is not null, then:
  1. Set response.[[complete]] to true.
  2. Assert: response.[[retryPromise]] is not null.
  3. Reject response.[[retryPromise]] with exception.
5. Otherwise, reject request.[[acceptPromise]] with exception.
6. Set request.[[updating]] to false.
Abort the algorithm.

Note

Abort the update runs when there is a fatal error updating the payment request, such as the supplied detailsPromise rejecting, or its fulfillment value containing invalid data. This would potentially leave the payment request in an inconsistent state since the developer hasn't successfully handled the change event.

Consequently, the PaymentRequest moves to a "closed" state. The error is signaled to the developer through the rejection of the [[acceptPromise]], i.e., the promise returned by show().

Similarly, abort the update occurring during retry() causes the [[retryPromise]] to reject, and the corresponding PaymentResponse's [[complete]] internal slot will be set to true (i.e., it can no longer be used).

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.

This section is non-normative.

For the user-facing aspects of Payment Request API, implementations integrate with platform accessibility APIs via form controls and other input modalities. Furthermore, to increase the intelligibility of total, shipping addresses, and contact information, implementations format data according to system conventions.

This specification relies on several other underlying specifications.

ECMAScript: The term internal slot is defined [ECMASCRIPT].

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words MAY, MUST, MUST NOT, OPTIONAL, RECOMMENDED, SHOULD, and SHOULD NOT in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

There is only one class of product that can claim conformance to this specification: a user agent.

Note

Although this specification is primarily targeted at web browsers, it is feasible that other software could also implement this specification in a conforming manner.

User agents MAY implement algorithms given in this specification in any way desired, so long as the end result is indistinguishable from the result that would be obtained by the specification's algorithms.

User agents MAY impose implementation-specific limits on otherwise unconstrained inputs, e.g., to prevent denial of service attacks, to guard against running out of memory, or to work around platform-specific limitations. When an input exceeds implementation-specific limit, the user agent MUST throw, or, in the context of a promise, reject with, a TypeError optionally informing the developer of how a particular input exceeded an implementation-specific limit.

WebIDL[SecureContext, Exposed=Window]
interface PaymentRequest : EventTarget {
  constructor(
    sequence<PaymentMethodData> methodData,
    PaymentDetailsInit details,
    optional PaymentOptions options = {}
  );
  [NewObject]
  Promise<PaymentResponse> show(optional Promise<PaymentDetailsUpdate> detailsPromise);
  [NewObject]
  Promise<undefined> abort();
  [NewObject]
  Promise<boolean> canMakePayment();

  readonly attribute DOMString id;
  readonly attribute ContactAddress? shippingAddress;
  readonly attribute DOMString? shippingOption;
  readonly attribute PaymentShippingType? shippingType;

  attribute EventHandler onshippingaddresschange;
  attribute EventHandler onshippingoptionchange;
  attribute EventHandler onpaymentmethodchange;
};

dictionary PaymentMethodData {
  required DOMString supportedMethods;
  object data;
};

dictionary PaymentCurrencyAmount {
  required DOMString currency;
  required DOMString value;
};

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

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

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

dictionary PaymentDetailsModifier {
  required DOMString supportedMethods;
  PaymentItem total;
  sequence<PaymentItem> additionalDisplayItems;
  object data;
};

enum PaymentShippingType {
  "shipping",
  "delivery",
  "pickup"
};

dictionary PaymentOptions {
  boolean requestPayerName = false;
  boolean requestBillingAddress = false;
  boolean requestPayerEmail = false;
  boolean requestPayerPhone = false;
  boolean requestShipping = false;
  PaymentShippingType shippingType = "shipping";
};

dictionary PaymentItem {
  required DOMString label;
  required PaymentCurrencyAmount amount;
  boolean pending = false;
};

dictionary PaymentCompleteDetails {
  object? data = null;
};

enum PaymentComplete {
  "fail",
  "success",
  "unknown"
};

dictionary PaymentShippingOption {
  required DOMString id;
  required DOMString label;
  required PaymentCurrencyAmount amount;
  boolean selected = false;
};

[SecureContext, Exposed=Window]
interface PaymentResponse : EventTarget  {
  [Default] object toJSON();

  readonly attribute DOMString requestId;
  readonly attribute DOMString methodName;
  readonly attribute object details;
  readonly attribute ContactAddress? shippingAddress;
  readonly attribute DOMString? shippingOption;
  readonly attribute DOMString? payerName;
  readonly attribute DOMString? payerEmail;
  readonly attribute DOMString? payerPhone;

  [NewObject]
  Promise<undefined> complete(
    optional PaymentComplete result = "unknown",
    optional PaymentCompleteDetails details = {}
  );
  [NewObject]
  Promise<undefined> retry(optional PaymentValidationErrors errorFields = {});

  attribute EventHandler onpayerdetailchange;
};

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

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

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

[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);
};

dictionary PaymentRequestUpdateEventInit : EventInit {};

This specification was derived from a report published previously by the Web Platform Incubator Community Group.

Changes from between CR2 until now:

Changes from between CR1 and CR2:

[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; 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. Adrian Hope-Bailie; Ian Jacobs; Rouslan Solomakhin; Jinho Bang. W3C. 25 January 2023. 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. 24 July 2024. 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. W3C Candidate Recommendation. URL: https://www.w3.org/TR/secure-contexts/

Payment Request API

Abstract

Status of This Document

1. Introduction

1.1 Goals and scope

2. Examples of usage

2.1 Declaring multiple ways of paying

2.2 Describing what is being paid for

2.3 Adding shipping options

2.4 Conditional modifications to payment request

2.5 Requesting specific information from the end user

2.6 Constructing a PaymentRequest

2.7 Handling events and updating the payment request

2.8 Fine-grained error reporting

2.9 POSTing payment response back to a server

2.10 Using with cross-origin iframes

3. PaymentRequest interface

3.1 Constructor

3.2 id attribute

3.3 show() method

3.4 abort() method

3.5 canMakePayment() method

3.6 shippingAddress attribute

3.7 shippingType attribute

3.8 onshippingaddresschange attribute

3.9 shippingOption attribute

3.10 onshippingoptionchange attribute

3.11 onpaymentmethodchange attribute

3.12 Internal Slots

4. PaymentMethodData dictionary

5. PaymentCurrencyAmount dictionary

5.1 Validity checkers

6. Payment details dictionaries

6.1 PaymentDetailsBase dictionary

6.2 PaymentDetailsInit dictionary

6.3 PaymentDetailsUpdate dictionary

7. PaymentDetailsModifier dictionary

8. PaymentShippingType enum

9. PaymentOptions dictionary

10. PaymentItem dictionary

11. PaymentCompleteDetails dictionary

12. PaymentComplete enum

13. PaymentShippingOption dictionary

14. PaymentResponse interface

14.1 retry() method

14.1.1 PaymentValidationErrors dictionary

14.1.2 PayerErrors dictionary

14.2 methodName attribute

14.3 details attribute

14.4 shippingAddress attribute

14.5 shippingOption attribute

14.6 payerName attribute

14.7 payerEmail attribute

14.8 payerPhone attribute

14.9 requestId attribute

14.10 complete() method

14.11 onpayerdetailchange attribute

14.12 Internal Slots

15. Shipping and billing addresses

15.1 AddressErrors dictionary

16. Permissions Policy integration

17. Events

17.1 Summary

17.2 PaymentMethodChangeEvent interface

17.2.1 methodDetails attribute

17.2.2 methodName attribute

17.2.3 PaymentMethodChangeEventInit dictionary

17.3 PaymentRequestUpdateEvent interface

17.3.1 Constructor

17.3.2 updateWith() method

17.3.3 Internal Slots

17.3.4 PaymentRequestUpdateEventInit dictionary

18. Algorithms

18.1 Can make payment algorithm

18.2 Shipping address changed algorithm

18.3 Shipping option changed algorithm

18.4 Payment method changed algorithm

18.5 PaymentRequest updated algorithm

18.6 Payer detail changed algorithm

18.7 User accepts the payment request algorithm

2.6 Constructing a `PaymentRequest`

3. `PaymentRequest` interface

3.2 `id` attribute

3.3 `show()` method

3.4 `abort()` method

3.5 `canMakePayment()` method

3.6 `shippingAddress` attribute

3.7 `shippingType` attribute

3.8 `onshippingaddresschange` attribute

3.9 `shippingOption` attribute

3.10 `onshippingoptionchange` attribute

3.11 `onpaymentmethodchange` attribute

4. `PaymentMethodData` dictionary

5. `PaymentCurrencyAmount` dictionary

6.1 `PaymentDetailsBase` dictionary

6.2 `PaymentDetailsInit` dictionary

6.3 `PaymentDetailsUpdate` dictionary

7. `PaymentDetailsModifier` dictionary

8. `PaymentShippingType` enum

9. `PaymentOptions` dictionary

10. `PaymentItem` dictionary

11. `PaymentCompleteDetails` dictionary

12. `PaymentComplete` enum

13. `PaymentShippingOption` dictionary

14. `PaymentResponse` interface

14.1 `retry()` method

14.1.1 `PaymentValidationErrors` dictionary

14.1.2 `PayerErrors` dictionary

14.2 `methodName` attribute

14.3 `details` attribute

14.4 `shippingAddress` attribute

14.5 `shippingOption` attribute

14.6 `payerName` attribute

14.7 `payerEmail` attribute

14.8 `payerPhone` attribute

14.9 `requestId` attribute

14.10 `complete()` method

14.11 `onpayerdetailchange` attribute

15.1 `AddressErrors` dictionary

17.2 `PaymentMethodChangeEvent` interface

17.2.1 `methodDetails` attribute

17.2.2 `methodName` attribute

17.2.3 `PaymentMethodChangeEventInit` dictionary

17.3 `PaymentRequestUpdateEvent` interface

17.3.1 `Constructor`

17.3.2 `updateWith()` method

17.3.4 `PaymentRequestUpdateEventInit` dictionary

18.9 Update a `PaymentRequest`'s details algorithm

19.1 User protections with `show()` method

19.8 `canMakePayment()` protections