HomeWork about Students

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>ya s2dent</title>
</head>
<body>
<script>
    class User {
        constructor(name, surname) {
            this.name = name;
            this.surname = surname;
        }

        getInfo() {
            return this.name + ' ' + this.surname;
        }
    }

    class Student extends User {

        constructor(name, surname, year) {
            super(name, surname);
            this.year = year;
        }

        getCourse() {
            var data = new Date();
            if (data.getFullYear() - this.year <= 6) return data.getFullYear() - this.year
            else alert('Already does not exist as El studento');
        }

        enroll(){
            //?
            //var isEnrolled = true;
            //var dataEnrolling = new Date();
            //if (dataEnrolling.getFullYear() - this.year = 0) return dataEnrolling;
        }

        expell(){
            //var isEnrolled = false;

        }
    }

    var student = new Student('Иван', 'Иванов', 2015);
    //student.enroll();
    alert(student.name);
    alert(student.surname);
    alert(student.getInfo());
    alert(student.year);
    alert(student.getCourse());


</script>
</body>
</html>