Trong JS, hàm là first-class object. Có thể dùng Constructor Function để tạo đối tượng.
Ví dụ
<html>
<head>
<title>User-defined objects</title>
<script>
function Book(title, author) {
this.title = title;
this.author = author;
}
</script>
</head>
<body>
<script>
var myBook = new Book("Amit", "Python");
document.write("Book title: " + myBook.title + "<br>");
document.write("Book author: " + myBook.author + "<br>");
</script>
</body>
</html>