Adds an event handler that runs when a product option choice is selected.
This function is currently only available for Wix Studio sites.
The onChoiceSelected() function adds an event handler that runs when a site visitor selects a product option choice such as {color: "white", size: "m"}.
The received selectedChoices object contains information about the product option choice that was selected.
choiceSelectedEventhandler(selectedChoices: object): void The function to run when a product option choice is selected.