$(window).on('changed.zf.mediaquery', function(event, newSize, oldSize) {
  modal();
})
modal();
function modal(){
  if (Foundation.MediaQuery.is('large') == true) {
      alert('large');
  } else if (Foundation.MediaQuery.is('medium') == true) {
      alert('medium');
  } else {
      alert('small');
  }
}