Polymorphism.js

function Champion(category = 'Champion') {
  this.category = category;
  this.sayHi = function() { console.log(`Hey, a ${this.category} is here`) };
};

function Warrior() {
  Champion.call(this,'Warrior'); 
}
           
function Dwarf() {
  Champion.call(this,'Dwarf'); 
}
        
function Rogue() {
  Champion.call(this,'Rogue'); 
}

const champions = [new Rogue(), new Warrior(), new Dwarf()];

// Using ES6 of
for(hero of champions) {
  hero.sayHi(); // Much cleaner
}

// => Hey, a Rogue is here | Hey, a Warrior is here | Hey, a Dwarf is here