Minimalist RPG example written with ES2015 syntax

rpg_es2015.js

class Character {
    constructor(name, health, strength) {
        this.name = name;
        this.health = health;
        this.strength = strength;
    }

    describe() {
        return this.name + " has " + this.health +
            " health points and " + this.strength + " strength";
    }

    attack(target) {
        if (this.health > 0) {
            var damage = this.strength;
            console.log(this.name + " is attacking " + target.name + " and deals " + damage + " damage points");
            target.health -= damage;
            if (target.health > 0) {
                console.log(target.name + " has " + target.health + " health points left");
            } else {
                target.health = 0;
                console.log(target.name + " has died !");
            }
        } else {
            console.log(this.name + " cannot attack: he's dead...");
        }
    }
}

class Player extends Character {
    constructor(name, health, strength) {
        super(name, health, strength);
        this.xp = 0;
    }

    describe() {
        return super.describe() + ", with " + this.xp + " XP points";
    }

    attack(target) {
        super.attack(target);
        if (target.health === 0) {
            console.log(this.name + " killed " + target.name + " and wins " +
                monster.value + " XP points");
            this.xp += target.value;
        }
    }
}

class NPC extends Character {
    constructor(name, health, strength, race, value) {
        super(name, health, strength);
        this.race = race;
        this.value = value;
    }

    describe() {
        return super.describe() + ". It's a " + this.race + " worth " + this.value + " XP points";
    }
}

console.log("Welcome to this adventure game ! Here are our fearless heroes :");
var player1 = new Player("Aurora", 150, 25);
console.log(player1.describe());
var player2 = new Player("Glacius", 120, 30);
console.log(player2.describe());

var monster = new NPC("ZogZog", 40, 20, "orc", 10);
console.log("An ugly monster is coming :");
console.log(monster.describe());

monster.attack(player1);
monster.attack(player2);

player1.attack(monster);
player2.attack(monster);

console.log(player1.describe());
console.log(player2.describe());