Seletor de consulta tem clas
if (document.body.classList.contains('thatClass')) {
// do some stuff
}
Comfortable Capuchin
if (document.body.classList.contains('thatClass')) {
// do some stuff
}document.body.classList.add('thisClass');
// $('body').addClass('thisClass');
document.body.classList.remove('thatClass');
// $('body').removeClass('thatClass');
document.body.classList.toggle('anotherClass');
// $('body').toggleClass('anotherClass');