checkout.on(event: 'change', handler: function) The change event is triggered when Checkout Session data changes, such as when the customer changes their shipping address. The event payload is always a Checkout Session object. - event The name of the event. In this case, change. - handler handler(session) => void is a callback function that you provide that will be called when the event is fired. When called it will be passed a Checkout Session object. ### Example title Listen to change events Is this helpful?