JavaScript patterns practice

Patterns.js

/*********************************************
*
*                Strategy
*
**********************************************/ 

const weapons  = {
	sword: {
		'name': 'Excalibur',
		'damage': 20
	},
	axe: {
		'name': 'Big Axe',
		'damage': 15
	},
	knife: {
    'name': 'little knife',
    'damage': 5
  }
};

function Character() {
	this.weaponName = null;
	this.weaponDamage = null;
};

Character.prototype.setWeapon = function(weapon) {
	this.weaponName = weapon['name'];
	this.weaponDamage = weapon['damage'];
};

Character.prototype.useWeapon = function() {
	if (this.weaponName  === null || this.weaponDamage === null) {
		console.log(`${this.name} is unarmed`);
	} else {
		console.log(`${this.name} used ${this.weaponName} and it made ${this.weaponDamage} damage`);
	}
};

function Knight(name) {
	this.name = name || 'Artur';
};

Knight.prototype = new Character();

function Troll(name) {
	this.name = name || 'Gtahllsue';
};

Troll.prototype = new Character();

let knight1 = new Knight();
let troll1 = new Troll();

knight1.useWeapon();
troll1.useWeapon();

knight1.setWeapon(weapons.sword);
troll1.setWeapon(weapons.axe);
knight1.useWeapon();
troll1.useWeapon();


/*********************************************
*
*                Singleton
*
**********************************************/

//Вариант 1

const object1 = {
	name: 'Object 1'
}; 

const object2 = {
	name: 'Object 2'
};

//Вариант 2

function Single() {

	Single.instance; 

	if (typeof Single.instance == 'object') {
		return Single.instance;
	};


	this.name = 'Big cat';
	this.isCat = true;

	Single.instance = this;

};

const obj1 = new Single();
const obj2 = new Single();

console.log(obj1 == obj2); //true

//Вариант 3

const Singleton = (function(){
	let instance;

	return function CreateSingle() {

		if (instance) {

			return instance;
		}

		this.name = 'Vasya';
		this.age = '25';


		if (this && this.constructor === CreateSingle) {
	
			instance = this;

		} else {
			
			return new CreateSingle();

		}
	}
})();