For Customer Authentication, the zingfit iframe will fire an event ( 'zingfitAuthentication' ) that you can listen for using the javascript snippet below. When the customer is authenticated the event will contain the customerId and firstName. With this event you will be able to do things such as:
know a customer is authenticated
display their name in the header
show a different set of menus when the customer is authenticated
function customerAuth(e){
if(e.detail && e.detail.customerId){
// customer is logged in
console.log('customerId: ' + e.detail.customerId);
console.log('firstName: ' + e.detail.firstName);
}else{
// customer is not logged in
}
}window.addEventListener('zingfitAuthentication', customerAuth, false);