<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
<script>
function myFunction() {
document.getElementById("demo").innerHTML = "Hello JavaScript!";
}
</script>
</head>
<body>
<h1>My Web Page</h1>
<p id="demo">A Paragraph</p>
<button type="button" onclick="myFunction()">Try it</button>
</body>
</html>