<!DOCTYPE html>
<html>
<head>
<style>
.democlass {
color: red;
}
</style>
</head>
<body>
<h1 class="democlass">Hello World</h1>
<p>Click the button to display the value of the class attribute of the h1 element.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var x = document.getElementsByTagName("H1")[0].getAttribute("class");
document.getElementById("demo").innerHTML = x;
}
</script>
</body>
</html>