PaymentMethodChangeEvent - Web APIs
options optional an optional paymentmethodchangeeventinit dictionary which may contain zero or more of the following properties: methodname optional a domstring containing the payment method identifier for the payment handler being used.

PaymentMethodChangeEvent - Web APIs
constructor paymentmethodchangeevent() creates and returns a new paymentmethodchangeevent object, optionally initialized with values taken from a given paymentmethodchangeeventinit dictionary.