<html>
<body>
<h1>JavaScript String Methods</h1>
<p>Convert string to upper case:</p>
<button onclick="myFunction()">Try it</button>
<p id="demo">Hello World!</p>
<script>
function myFunction() {
let text = document.getElementById("demo").innerHTML;
document.getElementById("demo").innerHTML =
text.toUpperCase();
}
</script>
</body>
</html>