Prevent .show if current step is not valid

[troykelly]

I'm not sure how to prevent a user going to a random step (for example steps are in the header) using the 'show' method when the current step is not valid.

eg:

            $('.checkout-steps a').on('click', function(){
                var gotostep    = $(this).data('gotostep');


               //if(the.current.step.is.valid()) {
                checkoutWizard
                    .formwizard('show', gotostep);
            });

Validation fails for fields on the page - but the user can go to the next (or any) step. The user can then submit the form (bypassing validation)