Object.size = function(object) {
    var size = 0
    for (child in object) {
        if (object.hasOwnProperty(child)) {
            size++
        }
    }
    return size
}

var database = {}
var store = {}

database.people = {}

database.amount = {
    money : function(name) {
        return database.people[name].money || 0
    }
}

database.append = function(name, money) {
    database.people[name] = {name : name, money : money}
}

database.money = {
    deposit : function(name, amount) {
        database.people[name].money += amount
    },
    withdraw : function(name, amount) {
        database.people[name].money -= amount
    }
}

store.inventory = {}

store.items = {
    shirt : {price : 50}
}

store.register = function(customer) {
    store.inventory[customer] = {}
}

store.getItems = function(customer) {
    for (belonging in store.inventory[customer]) {
        console.log(store.inventory[customer][belonging])
    }
}

store.purchase = function(customer, buy, quantity) {
    for (i = 0; i < quantity; i++) {
        if (database.amount.money(customer) >= store.items[buy].price) {
            database.money.withdraw(customer, store.items[buy].price)
            store.inventory[customer][Object.size(store.inventory[customer]) + 1] = buy || "unknown"
        }
    }
}

database.append("David Wilson", 0)
database.money.deposit("David Wilson", 100)

store.register("David Wilson")
store.purchase("David Wilson", "shirt", 2)
store.getItems("David Wilson")