<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<!DOCTYPE html>
<html>
<script type="text/javascript">
$(document).ready(function(){
$("button").click(function(){
$("h2.alterna").toggle();
});
});
</script>
<body>
<h2> Eu sou um h2 fixo</h2>
<h2 class="alterna">Eu sou um h2 da classe alterna</h2>
<button>Clique para alternar a visibilidade do h2 da classe alterna
</button>
</body>
</html>
