<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Callback</h2>
<p>Wait 3 seconds (3000 milliseconds) for this page to change.</p>
<h1 id="demo"></h1>
<script>
setTimeout(myFunction, 1000);
function myFunction() {
document.getElementById("demo").innerHTML = "I love You !!";
}
</script>
</body>
</html>