Accessing privates variables in shared methods on the prototype

prototype-private-access.js

// Was always interested if you can share private variables in prototyped methods.  And it looks like you can!

function Bank(name) {
    this.name = name;
    this.messages = [];
}
Bank.prototype = (function() {
    var money_total = 500000;

    return {
        withdraw : function(amt) {
            if (amt > money_total) {
                this.messages.push("The bank does not have enough money!");
                return false
            }
    
            money_total -= amt;
            this.messages.push(amt + " withdrawn from total leaving " + money_total);
            return true;
        },
        getTotal : function() {
           return money_total;
        }
    }
}());

var branch1 = new Bank("NY")
var branch2 = new Bank("CT")
branch1.withdraw(400000); // true
branch1.messages; // ["400000 withdrawn from total leaving 100000"]
branch2.withdraw(400000); // false
branch2.messages; // ["The bank does not have enough money!"]

// Version 2
// Heck, you could even do:
function Bank(name) {
    // private
    var money_total = 500000;
    
    // public
    this.name = name;
    this.messages = [];

    // Define prototype methods
    Bank.prototype.withdraw = function(amt) {
        if (amt > money_total) {
            this.messages.push("You don't have enough money!");
            return false
        }
    
        money_total -= amt;
        this.messages.push(amt + " withdrawn from total leaving " + money_total);
        return true;
    };
    Bank.prototype.getTotal = function() {
        return money_total;
    };
}

var branch1 = new Bank("NY")
var branch2 = new Bank("CT")
branch1.withdraw(400000); // true
branch1.messages; // ["400000 withdrawn from total leaving 100000"]
branch2.withdraw(400000); // false
branch2.messages; // ["The bank does not have enough money!"]

Performance tests: http://jsperf.com/function-prototype-with-private-variables