Flyweight pattern in a nutshell

Flyweight.js

function Flyweight (make, model, processor) {
    this.make = make;
    this.model = model;
    this.processor = processor;
};
 
var FlyWeightFactory = (function () {
    var flyweights = {};
 
    return {
 
        get: function (make, model, processor) {
            if (!flyweights[make + model]) {
                flyweights[make + model] = 
                    new Flyweight(make, model, processor);
            }
            return flyweights[make + model];
        },
 
        getCount: function () {
            var count = 0;
            for (var f in flyweights) count++;
            return count;
        }
    }
})();
 
function ComputerCollection () {
    var computers = {};
    var count = 0;
 
    return {
        add: function (make, model, processor, memory, tag) {
            computers[tag] = 
                new Computer(make, model, processor, memory, tag);
            count++;
        },
 
        get: function (tag) {
            return computers[tag];
        },
 
        getCount: function () {
            return count;
        }
    };
}
 
var Computer = function (make, model, processor, memory, tag) {
    this.flyweight = FlyWeightFactory.get(make, model, processor);
    this.memory = memory;
    this.tag = tag;
    this.getMake = function () {
        return this.flyweight.make;
    }
    // ...
}
 
// log helper
 
var log = (function () {
    var log = "";
 
    return {
        add: function (msg) { log += msg + "\n"; },
        show: function () { alert(log); log = ""; }
    }
})();
 
function run() {
    var computers = new ComputerCollection();
    
    computers.add("Dell", "Studio XPS", "Intel", "5G", "Y755P");
    computers.add("Dell", "Studio XPS", "Intel", "6G", "X997T");
    computers.add("Dell", "Studio XPS", "Intel", "2G", "U8U80");
    computers.add("Dell", "Studio XPS", "Intel", "2G", "NT777");
    computers.add("Dell", "Studio XPS", "Intel", "2G", "0J88A");
    computers.add("HP", "Envy", "Intel", "4G", "CNU883701");
    computers.add("HP", "Envy", "Intel", "2G", "TXU003283");
 
    log.add("Computers: " + computers.getCount());
    log.add("Flyweights: " + FlyWeightFactory.getCount());
    log.show();
}