shopping_list.js

// Program logic

function ShoppingList( options ) {
  this.items = {};
  this.defaults = options.defaults;
  if ( this.defaults ) {
    this.items = this.defaults;
  }
}

ShoppingList.prototype.addItems = function( items ) {
  for ( var item in items ) {
    quantity = items[item];
    this.items[item] = quantity;
  }
}

ShoppingList.prototype.get = function() {
  return this.items
}

ShoppingList.prototype.reset = function() {
  this.items = {};
  if ( this.defaults ) {
    this.items = this.defaults;
  }
}

// Now to use the functions

var List = new ShoppingList({
  defaults: {
    "fruit": 5,
    "vegetables": 3,
    "chips": 1
  }
});

console.log(List.get());
// => Object { fruit: 5, vegetables: 3, chips: 1 }

List.reset();

console.log(List.get());
// => Object { fruit: 5, vegetables: 3, chips: 1 }

List.addItems({
  "coke": 1
});

console.log(List.get());
// => Object { fruit: 5, vegetables: 3, chips: 1, coke: 1 }

List.reset();

console.log(List.get());
// => Object { fruit: 5, vegetables: 3, chips: 1, COKE: 1 } WTF - why does coke get added to this.defaults????