warrior.js

let warrior = {
    hp: 100,
    strength: 20,
    attack: function(target) {
        target.hp -= this.strength;
    }
}

let enemy = {
    hp: 100,
    strength: 12,
    attack: function(target) {
        target.hp -= this.strength;
    }
}

warrior.attack(enemy);

console.log(enemy.hp); // output: 80