Simple object pool with O(1) creation / deletion

ObjectPool.js

/**
  * Copyright (c) 2013 Ivo Wetzel.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  * 
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  * 
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
function ObjectPool(size, clas) {

    // Initialize the pool with the default objects
    this.size = size;

    this._objects = new Array(this.size);
    this._meta = new Array(this.size);

    for(var i = 0, l = this.size; i < l; i++) {
        this._objects[i] = new clas();
        this._meta[i] = {
            used: false,
            next: i + 1
        };
    }

    this._meta[this.size - 1].next = -1;
    this._firstAvailable = 0;

}

ObjectPool.prototype = {

    create: function() {

        if (this._firstAvailable === -1) {
            return false;
        }

        var index = this._firstAvailable,
            object = this._objects[index];

        this._firstAvailable = this._meta[index].next;
        object.init.apply(object, arguments);
        this._meta[index].used = true;

        return true;

    },

    update: function(dt) {

        for(var i = 0, l = this.size; i < l; i++) {
            if (this._meta[i].used) {
                if (this._objects[i].update(dt) === false) {
                    this._meta[i].next = this._firstAvailable;
                    this._meta[i].used = false;
                    this._firstAvailable = i;
                }
            }
        }

    }

};