Object pooling implementation

objectpool.js

function ObjectPool(Type) {
    this.Type      = Type;
    this.available = [];
    this.active    = [];
}

ObjectPool.prototype.create = function() {
    var args = [].slice.apply(arguments), self = this, inst, ret;
    if (this.available.length == 0) {
        var Temp = function() {};
        Temp.prototype = this.Type.prototype;
        inst = new Temp;
        inst.destroy = function() { self.recycle(inst); };
    } else {
        inst = this.available.pop();
    }
    this.active.push(inst);
    ret = this.Type.apply(inst, args);
    ret = Object(ret) === ret ? ret : inst;
    return ret;
};

ObjectPool.prototype.recycle = function(item) {
    var idx = this.active.indexOf(item);
    this.active.splice(idx, 1);
    this.available.push(item);
    item.reset();
};

function Vec2(x, y) {
    this.x = x * 1;
    this.y = y * 1;
}

Vec2._pool = new ObjectPool(Vec2);

Vec2.create = function(x, y) {
    return this._pool.create(x, y);
};

Vec2.prototype.clone = function() {
    return Vec2.create(this.x, this.y);
};

Vec2.prototype.add = function(vec) {
    this.x += vec.x;
    this.y += vec.y;
    return this;
};

Vec2.prototype.sub = function(vec) {
    this.x -= vec.x;
    this.y -= vec.y;
    return this;
};

Vec2.prototype.scale = function(s) {
    this.x *= s;
    this.y *= s;
    return this;
};

Vec2.prototype.neg = function() {
    this.scale(-1);
    return this;
};

Vec2.prototype.dot = function(vec) {
    return this.x * vec.x + this.y * vec.y;
};

Vec2.prototype.normalize = function() {
    var l = this.length;
    this.scale(l == 0 ? 0 : 1 / l);
    return this;
};

Vec2.prototype.reset = function() {
    this.x = this.y = 0;
};

Object.defineProperty(Vec2.prototype, 'length', {
    get: function() { return Math.sqrt(this.dot(this)); }
});





var a = Vec2.create(1, 2), b = Vec2.create(3, 4), c = Vec2.create(5, 6), d = a.clone();
console.log(Vec2._pool);

console.log('=============');

a.add(b).add(c).add(d);

a.destroy();
b.destroy();

console.log(Vec2._pool);

console.log('=============');

a = Vec2.create(7, 8);
b = Vec2.create(9, 10);

console.log(Vec2._pool);

console.log('=============');

a.destroy();
b.destroy();
c.destroy();
d.destroy();

console.log(Vec2._pool);

console.log('=============');