Adds an event handler that runs when the Add To Cart button on the Product Page is clicked.
The onAddToCart() function adds an event handler that runs when a site visitor clicks the Add To Cart 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.addToCartEventHandler(resume: Function, cancel: Function): void The function to run when the Add To Cart button on the Product Page is clicked.