payfal-paypal-glue.js

function showPayFastNotice(){
  jQuery('#pmpro_payfast_before_checkout').show();
}
function hidePayFastNotice(){
  jQuery('#pmpro_payfast_before_checkout').hide();
}

jQuery(document).ready(function() {
  //detect gateway change
  jQuery('input[name=gateway]').click(function() {
    var chosen_gateway = jQuery(this).val();
    if(chosen_gateway == 'payfast') {
      showPayFastNotice();
    } else {
      hidePayFastNotice();
    }
  });
});