Try this one:
<!doctype html>
<html>
	<head>
		<title>JS Window onload event</title>
	</head>
	<body>
		<h1>Welcome to Studytonight!</h1>
		<p>We hope you are enjoying the course.</p>
		<script>
			function showAlert() {
				alert("App loaded");
			}
			// write code here
			window.onload=showAlert();
		</script>
	</body>
</html>