Classical OOP

"use strict";
// Classical OOP

// Inherit
Function.prototype.inherit = function (parent) {
    this.prototype = new parent();
    this.prototype.constructor = parent;
}

// Base class
function Human(fname, lname, age)
{
    this.fname = fname;
    this.lname = lname;
    this.age = age;
}

// Student -> Human
function Student(fname, lname, age, grade) {
    Human.call(this, fname, lname, age);
    this.grade = grade;
}

Student.inherit(Human);

Student.prototype.introduce = function () {
    return "Hello! My name is " + this.fname + " " + this.lname + ", my age is: " + this.age + " grade: " + this.grade;
}

// Teacher -> Human
function Teacher(fname, lname, age, speciality) {
    Human.call(this, fname, lname, age);
    this.speciality = speciality;
}

Teacher.inherit(Human);

Teacher.prototype.introduce = function () {
    return "Hello! My name is " + this.fname + " " + this.lname + ", my age is: " + this.age + " my speciality is: " + this.speciality;
}