Enum in JavaScript

enum.js

var Enum = (function(foo) {
    var EnumItem = function(item){
        if(typeof item == "string"){
            this.name = item;
        } else {
            this.name = item.name;
        }
    }
    EnumItem.prototype = new String("DEFAULT");
    EnumItem.prototype.toString = function(){
        return this.name;
    }
    EnumItem.prototype.equals = function(item){
        if(typeof item == "string"){
            return this.name == item;
        } else {
            return this == item && this.name == item.name;
        }
    }

    function Enum() {
        this.add.apply(this, arguments);
        Object.freeze(this);
    }
    Enum.prototype.add = function() {
        for (var i in arguments) {
            var enumItem = new EnumItem(arguments[i]);
            this[enumItem.name] = enumItem;
        }
    };
    Enum.prototype.toList = function() {
        return Object.keys(this);
    };
    foo.Enum = Enum;
    return Enum;
})(this);


var STATUS = new Enum("CLOSED","PENDING", { name : "CONFIRMED", ackd : true });
var STATE = new Enum("CLOSED","PENDING","CONFIRMED",{ name : "STARTED"},{ name : "PROCESSING",});

assert("Diff Enumes with equalSign",false, STATE.CLOSED === STATUS.CLOSED);  // false;
assert("Compare with String",false, STATE.CLOSED === "CLOSED" );  // false;
assert("Compare String Value",true, STATE.CLOSED.toString() === "CLOSED" );  // false;
STATE.PENDING = "NOT_PENDING";
assert("Value cannot be changed",true, STATE.PENDING.toString() === "PENDING" );  // false;
assert("Same String value with equals method",true, STATE.PENDING.equals("PENDING") ); 
assert("Diff String value with equals method",false, STATE.PENDING.equals("CLOSED") ); 
assert("Same Enums with equals method",true, STATE.PENDING.equals(STATE.PENDING) ); 
assert("Diff Enums with equals method",false, STATE.PENDING.equals(STATUS.PENDING) ); 


function assert(test,expression,result){
    console.log("Result : ", expression == result, "=>\tfor", test);
}