constructorsAndPrototypes.js

function Grandfather(name, age, job) {
  this.name = name;
  this.age = age;
  this.job = job;
}

Grandfather.prototype.aboutMe = function() {
  console.log(`I'm ${this.name}, I'm ${this.age} years old and I'm ${this.job === 'retired' ? '' : 'a '}${this.job}.`);
};

let grandad = new Grandfather('Jonathan', 80, 'retired');
grandad.aboutMe(); // I'm Jonathan, I'm 80 years old and I'm retired.
console.log(grandad); // Grandfather { name: 'Jonathan', age: 80, job: 'retired' }

function Father(name, age, job) {
  Grandfather.call(this, name, age, job);
}

Father.prototype = Object.create(Grandfather.prototype);

let dad = new Father('John', 40, 'coder');
dad.aboutMe(); // I'm John, I'm 40 years old and I'm a coder.

function Son(name, age, job) {
  Father.call(this, name, age, job);
}

Son.prototype = Object.create(Father.prototype);

let son = new Son('Johnny', 18, 'student');
son.aboutMe(); // I'm Johnny, I'm 18 years old and I'm a student.

console.log(son instanceof Son); // true
console.log(Father.prototype.isPrototypeOf(Son.prototype)); // true
console.log(Grandfather.prototype.isPrototypeOf(Son.prototype)); // true
console.log(son); // Grandfather { name: 'Johnny', age: 18, job: 'student' }