<!DOCTYPE html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>JavaScript Undefined Data Type</title>
</head>
<body>
<script>
// Creating variables
var a;
var b = "Wel-Come to aimtocode!"
// Printing variable values
document.write(a + "<br>");
document.write(b);
</script>
</body>
</html>