Hello @Kartik,
Simply use classList.contains():
if (document.body.classList.contains('thatClass')) {
// do some stuff
}
Other uses of classList:
document.body.classList.add('thisClass');
// $('body').addClass('thisClass');
document.body.classList.remove('thatClass');
// $('body').removeClass('thatClass');
document.body.classList.toggle('anotherClass');
Hope it helps!!
Thank You!!