Adds an event handler that runs when the Buy Now button on the Product Page is clicked.
The onBuyNow() function adds an event handler that runs when a site visitor clicks the Buy Now button on the Product Page.
The event handler has 2 functions:
cancel() function stops a site visitor from proceeding with the Wix Checkout process.resume() function allows a site visitor to proceed with the Wix Checkout process.buyNowEventHandler(resume: Function, cancel: Function): void The function to run when the Buy Now button on the Product Page is clicked.