Constructor Functions

const Person = function (firstname, lastname, birthYear) {
  this.firstname = firstname;
  this.lastname = lastname;
  this.birthYear = birthYear;
};

const levin = new Person('Levin', 'Bänninger', 2007);
const matilda = new Person('Matilda', 'Johnson', 2009);
const jay = new Person('Jay', 'Smith', 2010);
console.log(levin, matilda, jay);

const john = 'John';

console.log(levin instanceof Person);
console.log(john instanceof Person);

Person.prototype.calcAge = function () {
  const currentYear = new Date().getFullYear();
  console.log(currentYear - this.birthYear);
};

levin.calcAge();
matilda.calcAge();

Person.prototype.species = 'Homo sapiens';
console.log(levin.species, jay.species);

console.log(levin.__proto__);

Person.hey = function () {
  console.log('Hey there 👋');
};

Person.hey();

const Student = function (firstName, lastName, birthYear, course) {
  Person.call(this, firstName, lastName, birthYear);
  this.course = course;
};

Student.prototype = Object.create(Person.prototype);
Student.prototype.constructor = Student;

Student.prototype.introduce = function () {
  console.log(`My name is ${this.firstname} and I study ${this.course}`);
};

const mike = new Student('Mike', 'Johnson', 2010, 'Computer Science');
mike.introduce();
mike.calcAge();