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<!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>