JavaScript Reference

Complete reference for the Unified Checkout v1 JavaScript SDK. This page documents every method and type in the SDK's public surface. For event names and payload shapes, see Events.

VAS.UnifiedCheckout(sessionJWT)

Factory function that initializes the SDK. Returns a frozen, immutable client interface (the returned object is passed through Object.freeze(), so its methods cannot be reassigned or removed after creation).

Parameters:

Returns: Promise<UnifiedCheckoutInterface>

Throws: UnifiedCheckoutError with reason CAPTURE_CONTEXT_INVALID if the JWT signature is invalid, or UNUSED_TARGET_ORIGINS if the current page origin is not in the JWT's targetOrigins list.

const client = await VAS.UnifiedCheckout(sessionJWT);

UnifiedCheckoutInterface

The client object returned by VAS.UnifiedCheckout(). All methods throw an Error if called after destroy().

client.createCheckout(options?)

Creates a new checkout integration instance.

Parameters:

CreateCheckoutOptions:

Returns: Promise<Checkout>

const checkout = await client.createCheckout({ autoProcessing: false });

client.createTrigger(paymentType, options?)

Creates a trigger for programmatically launching a specific payment method.

Parameters:

CreateTriggerOptions:

Returns: Trigger

Throws: UnifiedCheckoutError with reason TRIGGER_PAYMENT_TYPE_NOT_SUPPORTED if the payment type cannot be used with a trigger.

const trigger = client.createTrigger('PANENTRY');

client.createButton(paymentType, options?) (Experimental)

Creates an individual payment method button.

Parameters:

CreateButtonOptions:

Returns: PaymentButton

const button = client.createButton('GOOGLEPAY');

client.on(event, callback)

Subscribes to a client-level event. Returns an unsubscribe function.

Parameters:

Returns: Unsubscribe — a function that removes the handler when called.

Throws: Error if event is not a valid event name.

const unsubscribe = client.on('error', (err) => {  console.error(err.source, err.code, err.message);});// Laterunsubscribe();

client.off(event, callback?)

Removes an event handler. This method is permissive — calling it with an unknown event or callback does not throw.

Parameters:

client.updateToken(token) (Future)

Reserved for updating the session token without reinitializing the SDK. Not yet implemented — calling this method throws an Error.

client.destroy()

Permanently destroys the client. Emits a "destroyed" event, clears all event listeners, and marks the instance as destroyed. Subsequent method calls throw.

Idempotent — calling destroy() multiple times is safe.

client.isDestroyed()

Returns: boolean — true if destroy() has been called.

Checkout

Returned by client.createCheckout(). Manages the full checkout UI lifecycle.

checkout.mount(target)

Attaches the payment UI to the page and starts the payment flow.

Parameters:

CheckoutContainers:

Returns: Promise<string> — a transient token JWT (when autoProcessing: false) or completed payment result JWT (when autoProcessing: true).

Throws: UnifiedCheckoutError — see Error Handling for mount error codes.

// Sidebarconst result = await checkout.mount('#buttons');// Embeddedconst result = await checkout.mount({  paymentSelection: '#buttons',  paymentScreen: '#form'});

checkout.unmount()

Removes the payment UI from the page. The checkout is not destroyed, and mount() can be called again.

checkout.complete(transientToken)

Manually completes the payment flow. Only available when autoProcessing is false.

Parameters:

Returns: Promise<string> — the completed payment result JWT.

Throws: UnifiedCheckoutError — see Error Handling for complete error codes.

const token = await checkout.mount('#buttons');const result = await checkout.complete(token);

checkout.isMounted()

Returns: boolean — true if the checkout UI is currently mounted.

checkout.isDestroyed()

Returns: boolean — true if destroy() has been called.

checkout.on(event, handler)

Subscribes to a checkout-level event. Returns an unsubscribe function.

Valid events: "mounted", "ready", "unready", "unmounted", "destroyed", "paymentMethodSelected", "paymentMethodCancelled", "paymentMethodUpdate", "error", "*".

See the Events page for payload details.

checkout.off(event, handler?)

Removes a checkout event handler.

checkout.destroy()

Permanently destroys the checkout. Removes payment UI, cleans up iframes, and emits a "destroyed" event. Idempotent.

Trigger

Returned by client.createTrigger(). Programmatically launches a specific payment method.

trigger.mount(target?)

Launches the payment method UI.

Parameters:

Returns: Promise<string> — transient token or completed payment result.

const result = await trigger.mount('#payment-screen');

trigger.unmount()

Hides the payment method UI. The trigger is not destroyed.

trigger.complete(transientToken)

Manually completes the payment. Same interface as checkout.complete().

trigger.isMounted()

Returns: boolean

trigger.isDestroyed()

Returns: boolean

trigger.on(event, handler)

Subscribes to trigger events. Same event names and payloads as checkout events.

trigger.off(event, handler?)

Removes a trigger event handler.

trigger.destroy()

Permanently destroys the trigger. Idempotent.

PaymentButton (Experimental)

Returned by client.createButton(). Renders an individual payment method button.

button.mount(container)

Mounts the button into a container.

Parameters:

Returns: Promise<string> — transient token or completed payment result.

button.unmount()

Removes the button from the page. The button is not destroyed.

button.complete(transientToken)

Manually completes the payment. Same interface as checkout.complete(). Only available when autoProcessing is false.

Parameters:

Returns: Promise<string> — the completed payment result JWT.

button.isMounted()

Returns: boolean

button.isDestroyed()

Returns: boolean

button.on(event, callback)

Subscribes to button events. Returns void (not an unsubscribe function). Use button.off() to remove handlers.

button.off(event, callback?)

Removes a button event handler.

button.destroy()

Permanently destroys the button. Idempotent.

Types

AllowedPaymentType

A union of "PANENTRY", digital payment types, SRC payment types, and alternative payment method (APM) types.

Core types:

"PANENTRY" | "APPLEPAY" | "GOOGLEPAY" | "PAZE" | "CLICKTOPAY"| "CHECK" | "TMS_TOKEN"

SRC types (used internally for Click to Pay network routing):

"SRCVISA" | "SRCMASTERCARD" | "SRCAMEX"

Alternative payment method types:

"AFFIRM" | "AFTERPAY" | "ALFAMART" | "ALIPAY" | "BANCONTACT"| "BELFIUS" | "BLIK" | "BUYBOX" | "DOKU" | "DRAGONPAY"| "EPS" | "ESTONIABANKS" | "FPXONLINEBANKING" | "GRABPAY" | "IDEAL"| "INDOMARET" | "INDONESIABANKS" | "JENIUSPAY" | "KAKAOPAY" | "KBC"| "KCP" | "KLARNA" | "KREDIVO" | "LATVIABANKS"| "LINEPAY" | "LINKAJA" | "LITHUANIABANKS" | "MULTIBANCO" | "MYBANK"| "NAVERPAY" | "OVO" | "OXXO" | "PAY-EASY" | "PAYCO"| "PAYCONIQ" | "PAYPAL" | "PAYPO" | "PAYU" | "PIX"| "PRZELEWY24" | "RAKUTENPAY" | "SEPADD" | "SOFORT" | "THAILANDBANKS"| "TINKPAYBYBANK" | "TPNTHAILAND" | "TRUSTLY" | "UKBACS" | "VENMO"| "WECHATPAY"

See Alternative Payment Methods and Digital Wallets for descriptions and categories.

AllowedCardNetworks

"AMEX" | "CARNET" | "CARTESBANCAIRES" | "CUP" | "DINERSCLUB"| "DISCOVER" | "EFTPOS" | "ELO" | "JAYWAN" | "JCB"| "JCREW" | "KCP" | "MADA" | "MAESTRO" | "MASTERCARD"| "MEEZA" | "PAYPAK" | "UATP" | "VISA"

See Card Payments for descriptions.

UnifiedCheckoutError

An Error subclass thrown by SDK methods (for example, VAS.UnifiedCheckout(), mount(), complete()) when a call fails.

try {  const client = await VAS.UnifiedCheckout(sessionJWT);} catch (error) {  if (error.name === 'UnifiedCheckoutError') {    console.error(error.reason, error.message, error.correlationId);  }}