How to validate the booking form

file.js

$('form[action*="/cart/add"]').submit(function(e) {
  var btaForm = $(this).data('bta.bookingForm');
 
  if ((typeof(btaForm) != "undefined") && !btaForm.isValid()) {
    e.stopImmediatePropagation(); // prevents BTA's default form submit handler which also checks for validity
    return false;
  }
  
  // regular Ajax submit from here...
}