jQuery - Flag if element has CSS property display none

Question

var dfpBndrlElemPre          = '#div-gpt-ad-',
      dfpBndrlId               = '1542075954162-0', // banderole id 
      dfpBndrlFullId           = '.banderole' + ' ' + dfpBndrlElemPre + dfpBndrlId;

if(($(dfpBndrlFullId).css('display') == 'none')){ 
    $('.banderole').hide();
     console.log('banderole hide');
}
else {
  $('.banderole').show();
  console.log('banderole show');
}