Add and Remove Class with Javascript / Adicionar e Remover Classe com Javascript

add-remove-class.js

var variavel = document.querySelector('.title-main');

variavel.addEventListener('click', function() {

	if(variavel.classList.contains('classe')) {
		this.classList.remove('classe');
	}

	else {
		this.classList.add('classe');
	}

});

// Or

variavel.addEventListener('click', function() {

	this.classList.toggle('classe')

});