This script gist shows constructors in Es6 syntax for the "OOP in Javascript" article by Yasir Gaji

oopijall.js

  // BLOCK ONE
{
  class Entity {
    constructor(name) {
      this.name = name;
    }
  } 

  const human = new Entity('Creature'); 

  console.log(human); 
}

  // BLOCK TWO
{
  class Entity {
    constructor(name, dod) {
      this.name = name;
      this.creationDate = new Date(dod);
    }
    getTotalYears() {
      return new Date().getFullYear() - this.creationDate.getFullYear();
    }
  } 


  const human = new Entity('Creature', 'january 09 2000'); 


  console.log(human.getTotalYears()); 
  console.log(human); 
}


  // BLOCK THREE 
{
  class person {
    constructor(name) {
      this.name = name;
    }
    greets() {
      return `${this.name} says hi`;
    }
  } 

  const Yasir = new person('Yasir'); 

  class Entity {
    constructor(name, regards) {
      person.call(this, name); 

      this.regards = regards;
    }
  } 

  Entity.prototype = Object.create(person.prototype); 

  const MrSmith = new Entity('Mr.Smith', 'how are you?'); 

  console.log(Yasir); 

  console.log(MrSmith); 

  console.log(MrSmith.greets()); 
}